NYU & Columbia interview very early (Oct); others I interviewed at before Dec: BU, Georgetown, GW, Penn. It really depends on how early your application is completed, so apply EARLY!!
from my experience, all the ny state schools, penn state, and gw interview early. i think it was a little different last year with the amcas situation though.
some of these schools contacted me by phone late august to schedule interview in sept.
I think most schools start interviewing before the end of the year. Even with all the AMCAS delays last cycle, I had almost all of my interviews before January 1st, because I had all of my secondaries in before the end of September (and many of them before the end of August). So the take-home message is: APPLYING EARLY means you have a much better chance of INTERVIEWING EARLY.