I just booked mine this morning for the one that leaves from the Poly. They had others that leave from WL & Cont. You can book them 90 days out. The boat fits up to 10 adults + 2 children. The cost with tax is $140.84. I had to give them a credit card guarantee. You have 24 hours before the cruise to cancel.
I tried to book the Illuminations cruise for any night 8/13-8/20 but its booked for the week. But I'm more than happy with the Wishes cruise for our last night.