I have no idea, but they are always out on the UK travel agencies websites first. I know that Costa's are out, and I am guessing that RCCL's will be out there first ahead of the US website by a day or two. It would make sense that they release on the same day about itineraries and pricing, but it never does.
Atleast it gives us some idea about how the prices will run for the new sailings.
Have a good afternoon,