The question can be split into two parts:
1. Best time during a given year
2. Best year
1. In theory, the best time within a year to convert is when your T-IRA portfolio is at its nadir. Which is great if you can see into the future.
Pragmatically, waiting until there's a market correction (10% dip or more) can leave you converting at a higher value than converting now. If the market rises 15% while you're waiting and then drops 10% (to 103.5% of your starting value), what's the point? Or if you're planning on converting a bit each year, you can easily wind up stuck at the end of the year with a higher market still waiting for that correction.
If you're trying to keep MAGI under a certain "cliff" threshold (e.g. for ACA subsidies or to avoid IRMAA) then you should likely be conservative and top off your conversion near year end once you have a better handle on MAGI YTD. If your concern is about edging into another tax bracket, it's not a big deal if you wind up a few dollars over or under, so don't wait until year end for that reason.
2. If you're converting and paying taxes with non-IRA money, sooner can be better than later even if your expected tax rates in the future will be a little higher. That's because you're effectively adding money to your IRA by prepaying your taxes. (A dollar in a Roth is worth more than a dollar in a T-IRA.)
OTOH, many states give tax breaks for retirement income (including Roth conversions) once one reaches a certain age. So it can be advantageous to wait until then. You might convert between the time you reach that age and the time you retire and actually start drawing money from your T-IRA and/or pension (and possibly using up that tax break).
Several states give some sort of help on Medicare Part D prescriptions, where your income needs to be low enough to qualify. Doing Roth conversions earlier (even at somewhat higher tax rates) may help qualify for these or other income-related programs.
The largest such program is EPIC in NYS. Its income cutoff is decidedly middle class: $75K single, $100K married.
The rule of thumb short answer is the sooner the better (both within year and across years); just don't do too much in a single year and keep various income thresholds in mind. And if you're thinking of making charitable contributions, keep some money in the T-IRA so you have it available for QCDs.

Gentlemen, I really appreciate for your inputs. Last spring was a great opportunity to do a large conversion. Unfortunately many of us did not plan for it. Now we are evaluating which how much and which funds to convert per year. Great reminder that the tax table is for the adjusted gross income.
To reduce tax in retirement, we did few small changes. We switched our 401(K) to Roth 401(K) several years ago. Still we have rollover and traditional IRAs to consider for higher future tax and RMD. Higher retirement income incurs additional cost on Medicare premium and taxation on most of the social security benefit.

Note for below video: 2:42 minutes in length, with the first 45 seconds being a Powell lead in......then the fun info starts just near the 50 seconds mark.

That other kind of inflation, eh?
The prior wage inflation video will allow a few to buy one of these, although the typical sports fan will not likely be shopping just yet. A wee bit outside of a common sense budget, yes? Scroll down the text a tiny bit for the MSRP price. I did find one locally that had an employee discount of$9K.
Hey...........Remain Curious,
Catch

Is there a track record of the fund manager, Priyanka Agnihotri?

Priyanka Agnihotri has served as portfolio manager of the Fund since its inception in 2022. Ms. Agnihotri is the portfolio manager for the International Leaders strategy within the Global Equity team. Ms. Agnihotri joined Brown Advisory as a financials equity research analyst in June 2015 having formerly worked for Bernstein Research on the sell-side covering European financials. Prior to this, she began her career in 2009 as a buy-side analyst for Phoenix Asset Management Partners focusing on U.K. equities. Ms. Agnihotri earned her MBA in 2009 from Columbia Business School where she was a member of the Value Investing Program.

Another worthwhile "The Intelligent Investor" column from Jason Zweig. Enjoy.
ARTICLE

There is already a transition place in place for a number of years including Greg Abel, Ajit Jain, and Todd Combs. I believe Abel is the one responsible for investing in Apple and dumped IBM (a long holding for many years). Now Apple accounts for over 40% of BRKA portfolio.
https://barrons.com/articles/who-succeed-berkshire-hathaway-ceo-warren-buffett-51577375291

The CEO sent out an email apologizing for the problems people are having connecting to Schwab: Link
I’m on Quicken for Mac and switched over to the new Schwab connection early in the process and haven’t encountered any issues.

Not all is bleak today. Gold’s picked up $23.00 and the miners are up better than a half percent.

I am pretty sure "Mommie" Vanguard refuses to let you trade any short or leveraged ETF

It’s crazy in some ways. You can buy DFKG (down 12% today) at Fido w/o any warning. But you get one when you try to buy DFND - which isn’t all that risky. But it holds a 25% constant short position. Than there’s TMSRX, which can of course short equities, but prompts no warning. I haven’t come across anything you can’t trade at Fido. Just some hoops to jump through.

Cathy's down 7% today. I bought a tiny bit 15% higher a couple of weeks ago. I think she has the right ideas but got ahead of things. IT really depends on how good her analysts are in tech and biotech in particular
My son bought $2100 in 2018 and it quadrupled by last January. I tried to get him to lighten up but he refused. Unfortunately, he did listen to me and sold his TSLA a year ago May, after a 60% gain.. but he should have told Dad to butt out!
@Hank re national debt
The problem with US money printing is it will cover debt, but if inflation gets hold and interest rates rise, the interest rate service will make the deficit worse and worse

Just bought small stake in DKNG. Probably nuts. But since I got out at $42 it’s fallen all the way to $28.50 this morning. At just over 1% of holdings, it isn’t going to make a heck of a difference. Until the short sellers started pummeling it, it seemed relatively uncorrelated with most of the market - one of my priorities.

The SEC has issued several warnings on leveraged ETFs under its "Investor Alerts & Bulletins" since 2009 with most recent being in 2021. These explain that the leveraged ETFs work as indicate only over "days" and should be used only for very short-term trading. Actually, the 2009 warning caused a strong reaction from the ETF industry over the SEC defining short-term as "days" rather than other vague meanings of short-term. In 2020, the SEC issued rules limiting NEW leveraged ETFs to +/- 2x, but allowed existing ETFs with higher leverage to continue; strangely, it excluded leveraged ETNs (really sponsors' IOUs or debt instruments) from these restrictions.
2021 Alert https://www.investor.gov/introduction-investing/general-resources/news-alerts/alerts-bulletins/investor-bulletins-2
2020 SEC Rule https://www.sec.gov/news/press-release/2020-269
2009 Alert https://www.investor.gov/introduction-investing/general-resources/news-alerts/alerts-bulletins/investor-alerts/sec-finra

All ratings have been updated on MFO Premium site through November 2021, including MultiSearch, Great Owls, Fund Alarm (Three Alarm and Honor Roll), Averages, Dashboard of Profiled Funds, Dashboard of Launch Alerts, Portfolios, Quick Search, and Fund Family Scorecard. The site now includes several analysis tools, including Correlation, Rolling Averages, Trend, Ferguson Metrics, Calendar Year and Period Performance.
Pretty good! Finished late on 2 December (Pacific Time).

Munger wasn’t painting with a broad brush. His references were to certain segments of the U.S. market - plus crypto. Article not as complete as I’d like. But thought it worth sharing in light of this 97 year old’s reputation and experience. And note the cash pile Berkshire is sitting on.
“Munger, who was speaking after Berkshire’s cash pile hit new heights at $149.2 billion of funds in the third quarter, also said he was bullish on renewable energy.”
Article

ETF industry has +2x NUGT, -2x DUST and the reference is supposedly GDX. So, the sponsor does fine whether investors win or lose, or lose and lose (see 3 yrs below).
In the Stockcharts below, timeframe may default to 1 yr eventually, so reset times appropriately.
These futures-based work OK for short-term trading. Look at LINK 3Mo.
Now look at 3 yrs, and BOTH did worse than GDX. LINK 3 Yrs.
That is why the SEC and FINRA have investor alerts on these types of funds.

Came across this one today. It’s being suggested by some pundits as a hedge against your gold mining stocks falling further.
The description from Lipper:
“The Fund seeks daily investment results, before fees and expenses, of 200% of the inverse (or opposite) of the price performance of the NYSE Arca Gold Miners Index. The Fund creates short positions by investing at least 80% of its net assets in: futures contracts; options on securities, indices and futures.”
DUST is off -71% over the past 3 years. Think I’d rather fry along with some mining stocks than try to catch this one. Gold’s been in a see-saw all year, bouncing between $1700 and around $1850. It appears to be on its way down again after topping-out only a few weeks ago.Just below $1800 at present. But this kind of erratic behavior is pretty typical. Limit your exposure. Don’t chase on the way up or down.

I've been following this post with interest. I don't use Quicken, but I did have a problem with an external account linked to Schwab, my 401k with TRP. I view my TRP account through Schwab because it makes it easier to see everything together on one site for charting and total portfolio break-down purposes. In any case, that account link was lost for a few days last week. Seemed to come and go actually. Now when my summary account data charts I have these huge excursions down ​and back up on the chart. Ugly but I know it's not real.
Since I don't use Quicken, this external account link problem I had may not be related to the discussion here, but it sure seems like a glitch on the Schwab side.

This is the online tax estimator that I use:
https://www.dinkytown.net/java/1040-tax-calculator.html
It is no cost and easy to do my what-ifs and see what happens.
Dave

With the public schools so messed up I am putting aside money for private school for the grandkids.

+1. Actually a good idea.

@BenWP - ex & distribution dates but no amounts given.
Brown Advisory Mutual Funds