It is uncommon to offer interview dates during the first week of November (AAMC annual meeting), the day before or after Thanksgiving, and the week between Christmas and New Year as these are times when deans/directors of admission are not available. You can figure that 2-4 weeks before each of those time periods, the invitations to interview will slow. So, some invites may be going out now for the time up through Dec 22 but you'll see a taper as we get close to that winter break period. Some schools will send another bunch out in mid-Dec for Jan/Feb.
You can also figure that schools that interview on Mondays will take off MLK Day in January but that's usually just one day.