The deans announced the September date on the paperwork provided in November, so this is hardly news (well, unless you did not bother to read said paperwork).
Relax... unless your application stinks, it will not be a problem. Friends from last year's application group (even some that took the August MCAT) are currently matriculating at UPenn, Columbia, Harvard, Yale, etc.
Wouldn't a serious premed have been thoroughly versed in the application process and perhaps inquired about the committee letter process (a crucial component) BEFORE selecting the program? I am not one to defend Columbia's program (it certainly has its faults), but YOU are culpable if you feel slighted on this issue.
ETA: Culpable especially since I see that you are applying for a second time so the committee's timeframe is definitely NOT a suprise.