You've got plenty of time. The Boobs Cruise tends to fill up pretty quickly with major groups and hollidays such as halloween. For the time you listed you should be fine. You can watch the list and if it starts to get full just sign up then. Or, sign up now and don't worry about it again! You'll have a great time!
Here is the booking link. Cancun Boobs Cruise Booking Page | Cancuncare. I think there is a list posted usually about a month before the actual cruise date.
Personally I would book right away so you don't have to worry about it selling out. If your situation changes you can always cancel for a full refund up to 48 hours before hand.
