I don't think there is an official deadline, most DO schools want large periodic deposits that is when most people drop the schools they are not going to attend.
Oh thank you! I really appreciate your answer. What happened is that I sent in the deposit for my second choice school then got accepted to my first choice school and sent the deposit as well. Now I'm vacillating between the two, just hoping someone could tell me if/if not there's a deadline.
Why does it matter what the deadline is, or if there even is one? You already said that one school is your "first choice", and you got into it. Sounds like you already made the choice. 😛