^i agree with jamesd. if you're submitting stuff in late august, you're already at the beginning of the big bulk of ppl applying. by even mid august, most of the top schools (re: all the ivies, cali schools, etc) are sending out interview letters to the "early" applicants.
if you know what you want, why not just apply as early as possible? if your LORs are already in order, i'd say apply during mid may when the application first becomes available. you can always update later. by the first week of june last year, the AADSAS number was already up to 1000.