I can't remember if we did with Ds1 or Ds2, but for Ds3 they said that they do them on an as-needed basis. They said not to schedule one for Ds3 (which I think had as much to do with me being an experienced mom as DS being developmentally on track).
Mine doesn't even do a 3 year appointment. Says not covered on ohip anymore. So no appt between 2 and 4 unless you have concerns which is bullshit. I go to a pedi and friends who have an np still get a 3 year.