The prices in the list of room rates say they're for "May 19-21", but it's not clear to me which nights this includes exactly. Are these rates for checking in on the 19th and checking out on the 22nd (3 nights)? Or checking in on the 18th and checking out the 22nd (4 nights)? Or something else? My guess is that it would have to be 4 nights (because otherwise these rates would be more expensive on a per-night basis than the per-night rates), but it'd be nice to have this confirmed and spelled out explicitly on the wiki page.
I imagine a lot of people, especially those traveling from far away, will need to arrive on the 18th, especially if the event starts in the morning on the 19th (the program page is unclear on that).