Check out mdapplicants.com. I think if you review specified dates for interview and acceptance for a given school across several profiles, you can get some vague idea of the turn-around time (taking into account snail mail time, of course, if decisions are delivered via regular mail). I'm also thinking that it probably depends on when a given individual's interview fell in the committee review cycle, so take it with a grain of salt.
However, I wouldn't concern yourself over it too much right now. Try to get complete at the schools without unnecessary delay. The sooner you get complete, the sooner you are likely to get an interview. Interview well, if invited. That is what's important at present. I think schools usually give you some idea of when you should be hearing from them after an interview.