Military rates at 90 days or less out. Sometimes there is a Florida resident deal. Close to sailings they may offer *GT rates that are reduced, but you have no choice of room. You get what you get and it is usually assigned very close to sailing date, if not on the day you arrive at the port.
Edit: I was not clear on the room thing...you buy a category live inside, oceanview, etc. and that is all you know...you wont get to pick location or deck of your room with the IGT,OGT. VGT rates.