March 17-19th or March 31st-April 2nd. I haven't signed up for anything yet because I haven't heard back from everywhere, though I think the weekends can fill up pretty quickly.
Congrats! They do have scheduled visits. After the acceptance email I got an email from a POI a few days later with info about the visit dates for my division.
Got an acceptance email from a POI from UPenn a couple hours ago! From previous years it looks they admit people into feb so they are probably still going through apps. I wonder too, based on the way they wanted the SOP formatted, if they don't admit by sub-field in which case notifications could be spread out.