Unless you have a lot of trips in the last 3 years that puts your physical presence at risk, you don't need to offset your 20 day trip. You can file in the 90 day window (if you never had trips lasting over 180 days for a single trip in the last 3 years)
Also, I don't think your calculation is correct. 26 Feb 2025 minus 90 days is November 28, 2024. 90 days is not the same as 3 months.
Given November 28, 2025 is Thanksgiving, just file the following Monday, December 2 to be on safe side.