All depends on you. I'm always warm, my wife complains of her neck being cold. We just got back from a Britash Aisle Cruise and both felt the cabin was too warm lots of time even though room temp. was set on the coolest setting. One area that gets most people is going to breakfast or lunch and crossing the area where the pools (deck 10 on Crown Princess) the wind can blow quite hard and of course on the top decks.
Layered works best for planning and then you decide.
Enjoy your cruise. We cruised several times (we thought) when we were first married, tools the kids on a few and then stopped till retirement a few years ago. Now in two years we have done 4 with a 15 day,2x 12 day and 7 day. Talking to people on the ship many have done 30-40 cruises and some of those 56 day cruises.
Bart