You didn't mention your filing status but look out for the long term cap gains on the 36k once your income goes above a certain level the tax on that moves from 0% to 15% which will cost $5400. If you don't have any other income there should be some minimal amount of Roth Conversion which together with the RMD would offset your standard deduction (plus the additional $6k deduction form the 'big bill' for over 65s), and still keep your LTCG rate at 0%. Above that amount you would start paying tax and the effective tax rate on that additional amount of Roth Conversion may be quite high when you take the jump in LTCG into account.
Check your safe harbor for estimated tax (see Form 2210 lines 1-9), the smaller of 100% of 2024 tax (110% if AGI > 150k or 75k if filing MFS), or 90% of 2025 tax. If 2025 is a big jump in income when you start doing Roths then you would probably base this off 2024 tax. Either way you may need to pay Q4 ES and then file Form 2210 AI to avoid a penalty.
If you continue to do Roth conversions annually, the advantage of a low prior year tax goes away and you should pay quarterly ES. If you base the quarterly ES off prior year tax going forward it's a fixed known amount and it doesn't matter when you do the Roth conversions, and rather than waiting til year-end you do them right away to take more advantage of the tax exempt growth (i.e. you could do your 2026 Roth conversion in January not December).
If able, pay tax electronically and directly at irs.gov rather than checks/vouchers etc.
But these are considerations and tax math your wealth and accounting people should cover.
