NPC Teen & Collegiate Nationals HELP!

Hey guys, could somebody explain how the first two days of the show go? I know thursday is weigh in’s, but here is what confuses me…
Friday p.m. is pre judging, yet saturday a.m. is listed as pre judging as well… then saturday night is finals and so on.

How does the two pre-judgings work? Is one of hem just for masters and the other for the teens and collegiate etc. the following day? I ask because a couple of friends and I are planning on going to the show this summer, and want to know what is worth buying tickets for. Any help is appreciated. Thanks a lot.

N.