All the PNM's have to report to the Union Great Hall at a certain time (I think the year I went through we had to be there at 4:30) and we're given an envelope with our bid inside, but we take it into the huge room and have to stand on top of the envelope (
) and wait until after we watch a video with all the sororities on campus and a "Go Greek" video. Then the Greek advisor makes a speech, then the Panhellenic VP of Recruitment makes a speech, and then the Rho Chis are revealed (they do the switching of letters at our university, too, but as an upperclassman, I knew that most of them were in a different sorority than they "reaffiliated" with
) After that, we pick up our envelopes, and then are permitted to open them and find out where we received a bid to.
The year I joined, my chapter didn't have a Rho Chi, so one of the Delta members came to the Great Hall to meet all the NM's. We got together with her, and she taught us a few cheers to sing on the way to the CR.
All the other chapters leave the Great Hall and go back to their CR's, but some of the sororities meet elsewhere around campus and then go out to celebrate elsewhere.
Our bid day we went to our chapter room, took pictures, ate food, and played some "getting to know you" games, and then the NM's had their first Alpha Education session. We did our Alpha ceremony the next night.