Not by much pre-announcement... gotta be ready using past cruise date releases as a guide. Typically, platinum and gold book one day prior to silver Castaway Club members, and then general public. This can be the difference of hundreds of dollars, or, in some cases (such as previous Hawaiian cruises), no availability at all in some categories.
There's a sticky with this info (which I helped compile, years back), but I've been out of the loop a while. Sometimes it is weeks of waiting from dates of previous release dates, and the chatter on the boards will increase on the new releases, but having a general idea helps to get prepared.
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