For 2007, I interviewed at MCG ~October 20th and then at Mercer ~November 7th.
Fort 2008, I interviewed at both MCG and Mercer in Feb. once my applications were finally completed in December (had to do some extra paperwork for in-state residency).
From my understanding, you get ranked by both of your interviewers and then, based on that ranking, your folder gets futher examined by the rest of the committee. Then, after that, there's a final ranking/vote on your folder that establishes your competativeness.
So, if you do well in your interviews, but your stats are not that great, you might be waitlisted still by the committee. Or, lets say you have great stats and a decent interview, you might not be presented to the committee until March b/c you get ranked behind other folders by your interviewer.
That's my theory atleast.