Many schools don’t require you to list them as first choice until after you are accepted. There are a few, however, that require you to designate them as first choice in Feb/Mar.
This thread might help. National Merit Scholarship First Choice School
Edit to tag @amsunshine if she is still around. She knows a lot about first choice deadlines. You can also try to read through last year’s thread where a lot of questions were discussed. Class of 2021 National Merit Thread - #230 by QQsubs