If your application isn't going to be complete until the end of September, you will be considered rather late in the cycle. This all depends on your GPA and DATs. I have a friend who applied late September (as in submitting AADSAS) and the schools didn't receive his supplementals until November. He still had quite a few interviews, but that's because he also had 3.9 from a top 25 university, had a DAT of 22, 23, and 24 across the board, actually published a paper and has done a ton of volunteering at his dental office. He even interviewed at a few Ivy league dental schools and got waitlisted/late acceptances. He was just so late in the game.
Really take a look at your stats and think about how confident of an applicant you are. If you want to share your stats, others might be able to comment more.