Because predents doesn't exist any more and digging through old threads can be tedious, here's my timeline from a couple cycles ago that may or may not be helpful; it seemed similar last year:
first batch (June 27)
supplemental received (July 28)
interview invite (Aug 30, probably first day)
interview (September 13, first day)
Supplemental was $50 (might have increased now) and a form/waiver. Supplemental was mailed back the same day I got it (from west coast). Their supplements come out in batches. The theory is that the number in the upper righthand corner of the PDF corresponds to that wave of supplements sent out.
I was also only given two weeks notice for an interview with no other option (I think they hesitated to offer another date when I called to schedule). I believe this is on purpose. Good thing I had a free flight. Show them you want it and make it happen if you get such short notice. I had to change my school schedule to make it early in the semester to make it.
Lastly, there's a 90% chance admissions will read this thread. One of the few schools that I believe actually do come on here.