All that really matters is consistency. 20:4 should work fine, but theoretically 23:1 would work better since the eating window is smaller.
As long as whatever you choose, you do not break that eating cycle until you are done. It’s too easy to make up excuses to eat outside your window: there’s holidays, birthdays, special events all year round.
You can work your way upto rolling 48’s, they are pretty effective.
If you’re not familiar with the term, basically it means back-to-back 48 hour fasts usually with a one meal break or small eating window of a few hours. You can structure your breaks however you want ofc.
Edit: spelling
If it helps, fish (salmon in particular) is by far the most satiating food that is low in calories relative to the amount consumed. Well at least it satiates me really well… I eat it as my omad for a couple days if I really need to cut fast for whatever event, just because a little salmon really fills me up quickly and for a long time.