How many programs did you apply to? Are you an IMG or AMG? Are your step scores decent? It's still early in the game. Apps have only been out for two and a half weeks, and programs didn't receive the full app (Dean's letter/MSPE) until October 1st, so some places have only just now started looking at applications. I'd start worrying if you don't hear anything towards the end of October. If you didn't apply to too many programs, maybe add some more programs to your list.