I'm applying both MD and DO this cycle, and the DO schools sent out interview invites before I even got a couple of the MD school secondaries! It seems that PCOM hasn't started interviewing yet, but my other DO schools have sent me interview invites. I've only heard from one MD school so far post-secondary.
Last year I was an August MCATer - nothing in my file has changed significantly (other than I graduated). Last year I got ZERO interview invites. This year I have four so far. What I did last year (and DO NOT DO THIS) was not have my files absolutely complete except for my scores. I waited and lolly-gagged on my secondaries. My LORs weren't sent until mid-late November. DO NOT DO WHAT I DID LAST YEAR. To have the best chance as an August MCATer, you need to push your secondaries out the door NOW. Have your LORs sent NOW. The only thing holding up your application should be your scores. I know several people who were complete the day scores came out and were offered interviews literally the next day.
If you do well on the August MCAT you'll have no worries (as long as your files are complete the day scores come out). Oh, and look up the essay questions for those schools that won't send secondaries until scores come out - if you have those ready before October, you can turn those secondaries around within one day.
Good luck y'all!!!!!