Maternity Leave for teachers

Curious if you need a doc note to start your leave if it’s a little early before Due Date- early as in about 4-5 days earlier? I told my admin I’d work up until I physically felt I couldn’t (I’m a prek teacher, we on our feet A LOT). I’m due the 16th but we are talking early induction prob 13th or 14th. I’m trying to make it through this Wednesday or Thursday but I’m not sure I’ll be able too.

So in short, is it a personal decision where you tell your admin you are starting leave or do you need a physically note from OB telling them you can start leave early?