Well, AG tests the game, so that could take some time. Also, not every game will be accepted. ALSO, it could be three days, or even three weeks! Just be patient because I think they will try to contact you.
and now i'm trying to make my own little 8-Bit music for it using this mario composer thing. anyone ever used it? i need to know how to export the music into a .wav format or something...
They may just push it aside. Or they may tell you that it was rejected. As long as you made it and it is appropriate for the site it should be accepted.