I was on the Fantasy that docked the Saturday after Ian came through. As of Friday night, we weren't even sure if we would be able to dock on time because the Coast Guard had to clear Port Canaveral to reopen. So
DCL will give as much notice as they can, but in some cases they might not have much lead time because some decisions are out of their hands. They also may have to juggle ships scheduled to dock that get delayed (also happened when I was on the Fantasy; the Wish was supposed to dock Friday and got pushed back to Sunday, the scheduled Wish sailing for Saturday got canceled).
With that said, Nicole doesn't look to be nearly as nasty as Ian was, though as
@DCLCruiseFan09 said it could be a direct hit to PC. With Ian, MCO and PC were both closed for I think at least 2 days? If PC takes any damage from Nicole it could be closed for a bit of time. In order to clear PC for reopening they have to wait until the winds die down, the water is clear, and it's daylight (according to what we were told on the Fantasy).
All that to say, I would be prepared for some possible disruption. If something happens, then you're prepared, and if nothing happens, then things turned out better than you expected.