Disney Cruise Line has changed how old you have to be for a Disney Cruise. Starting immediately the infant age limit has been raised from 12 weeks to 6 months of age for any cruises that sail after January 1st, 2015. If you are sailing a Transatlantic, Hawaii or Panama Canal cruise, the minimum age has been increased to 1 year of age.
If you booked your Disney Cruise before July 18th, 2014, you are grandfathered in under the old rule and your infant just needs to be 12 weeks of age to cruise.