I don't really know much about the nursery because we didn't start cruising until our youngest was 4 (nearly 5) so neither she nor her sister ever needed the nursery. They love the club/lab though which is basically one BIG kids club, joined by a 'secret tunnel/passageway'. You don't need to sign them up for any time at the club/lab, as long as they have their band (which you will get once you check in at Port Canaveral) they can go in whenever you/they want during the cruise. If one side is in 'open house mode' (which means parents and siblings of different ages can come in) then secured programming is happening in the other side and no adult can enter when the club/lab is in secure mode except obviously when you go to pick up your child. Only one parent/adult can go in to pick a child up so if both my husband and myself go to get our kids (our oldest usually has self check out though) only he or I can actually enter the club/lab to get the kids while the other must wait outside.
Hope I haven't made it sound too complicated lol It's really quite simple to utilize the kids programming. On
Castaway Cay day, the club/lab on the ship closes and it 'moves' to the island and is called Skuttles Cove. While this is going to be our 5th cruise it's only our second time going to Castaway and we never used Skuttles Cove the first time. We are planning on using it this time as we have a 2pm mojito tasting booked at one of the bars on Castaway