This thread was last year's "Interview" thread. People posted when they got interview invites, might be interesting to read. Overall it kind of varied.
I got my first interview the week after I submitted my ERAS (I submitted a few days after 9/1). By the end of September I think I had 6-7. By the end of October I had all but 2 or 3. Got the last invite middle of november. It happens a bit earlier than other specialties, so I would try to submit before too much of september goes by. Only a couple of programs wait until your entire application is in before they send out their answers. It definitely differs from program to program though. Some assess every application as it comes in and decide very quickly to interview or not. Some wait until they get a certain number, then decide on those. Some wait until applications are complete or at least have certain important thinigs.
Interviews themselves can start as early as early october (I don't know of any september interviews). My first was middle of october. They run the new year. Some programs stop interviewing in January, some go until the end of february. It will all become clearer soon! Hopefully you will all post your interview invites this season too, it helps other people know which programs are sending out invites (or rejections).