Yes, you will be behind a little bit and it really is a slight disadvantage, but if your application is strong you should still be fine. As soon as you get your secondaries, get cracking on them asap. I did this last year after taking the Aug MCAT and was complete by the first week in Nov. at all my schools (regarding secondaries). Your interviews will likely be in the spring semester, and half the class may already be full, but that still leaves ample room for you. Good luck