Birthday Cruise Help...

[tgsx4]

Does anyone have any tips on how to "get in line" or Better My Odds for a birthday cruise when the reservations for that week are already filled up? I don't know when to call or when the cancellation period begins. I am trying for my 4, turning 5, year old and thought it would be a great big surprise but didn't find out about the cruise till too late. Same goes for the Treasure Hunt the originates out of the Grand Floridian.

Thanks!

Trying to make a trip to remember (but still learning!)