3 concerts nightly at 5:30, 6:45 and 8:00. 45 minute sets (sometimes they do run a little bit long but most of the time it is right around 45 minutes.)
If you aren't buying a dinner package or eligible for the Sat/Sun/Mon Chase wristbands, then you would be getting in line at the far right of the theater. How long you need to wait will depend on how popular the act is. Later concerts are often less crowded than earlier ones.
They let the package guests in and then the regular guests. If it's a day for Chase wristbands they probably have a couple rows blocked off for them until about 10 minutes before the concert.
Many times, especially later shows, you can just wander in 10-15 minutes before the show starts and find a seat, especially the later concerts. You probably will be sitting outside the overhang though, so watch the weather, and if you have a large party it would be more difficult to have the group sitting together in one row. If it's a more popular act you may just want to get in line at least 45 minutes before the show time though.