I think the answer of how much to pay depends on which is smaller - 90% of 2024 tax or 100% of 2023 tax (110% if AGI > 150k) etc, see https://www.irs.gov/faqs/estimated-tax
Due to the Roth conversion in Dec, when you do the final filing you may need use Form 2210 to reflect the uneven tax liability & payments throughout the year, otherwise there may still be a penalty even if you meet the minimum total.
I'm just going thru similar process myself for a Roth conversion in Q4; I put draft totals into TT to confirm the Q4 ES by looking at the penalty calculated on Form 1040.
