You cannot see the exact schedule until 45 days before your cruise sails, but in general:
Blue Man Group 4 nights per week, 2 shows each night
Legends at Sea - 3 nights per week, 2 shows per night (Main showroom)
Legends Unplugged - Manhattan Club - 3 nights per cruise - one show
Cirque Dreams - 2 shows per night, I believe four nights per week.
Second City shows several times - you will have no problem.
The only shows you need to really plan ahead on are Cirque (seating is limirted) and Legends at Sea in the main theater - it onlyshows 6 times, 680 seats each, for almost 5000 passengers total capacity.