When I went through (and I think it's still this way right now), the party before pref was Theme night (AKA skit night). We could go to a max of four parties, but at that point I was dropped to three sororities.
Unfortunately, I wasn't able to go to the party before pref
I had a test for my major (at the time) down at Ball State early the next morning (due to some misinformation, I registered to take the test at the nearest test center to me that wasn't my university, and later found out the test WAS offered at my school that same day
), so I had to write a letter for all the sororities to let them know why I was unable to attend parties that evening.
If I HAD been able to attend, I would've been attending the parties of ADPi, Tri-Delta, and KD.