Icarus
Congratulations to everyone who got an interview invite.
I am a R1 admit and wanted to say that I only got my invite 1 week after the "R1 deluge". Ironically, I was incessantly checking my email in anticipation of receiving an interview call from another school when I received my invite from HBS. So, for the people who did not get an interview invite today, although the situation may look bleak, do not lose hope. Concentrate on other applications/interviews coming your way and hope for the best.
I hope to see most, if not all, of you in Cambridge this fall.
I`
BUT, R1 was different:
"We expect to begin sending out interview invitations on October 16. This year we may not be trying to send as many out on one day as we did last year... maybe more like a not-scientifically-measured stream until December 15. We really (really, really, really) don't know how many will go out on any given day. If you call and ask, we will say exactly that."
Thanks for the encouragement, though!

but actually around 750 invites went out on Oct 16th. The R1 applicants were amazed to see around 750 spots getting picked up as soon as the interview scheduler went online. We R1 applicants had endless debate on why did they send out 750 invites on day 1 when they had advertised otherwise. So it wasn't different at all.