One of these is from Harmony, the other Serenade. Harmony was 2017 but Serenade was 2018. I don't recall which is which is which.
Both state WN (Southwest) is 11:30am to 6pm. Other airlines allow later flight times. Southwest I've heard has a small storage area at FLL so they can't hold bags longer. Plus Southwest when I have flown them is a stickler for the 4 hour rule not allowing bags to be checked before 4 hours prior to flight time.
Note you have to do this several days before the end of the cruise. On Serenade I had to ask for the form. When I saw another guest carry one into an elevator I realized my cabin attendant didn't deliver one to my cabin.
They not only checked my bags but also printed my boarding passes. I'm elite with Delta so I get free checked bags. This was respected and I was never charged. This is why it has to be done several days prior - so they can validate any fees and flight times with each airline. Even though you are on WN they have to verify flight times and the airline has to 'accept' your bags against your flight reservation days prior so it's not just about the fees or lack of.
Strangely enough, Deck 4 chairs by the shuffleboard court! While our wives were off at cupcake class, my son and I just sat there, shared a drink and talked life. Most relaxing moment of the trip (even though neither of us cared for the drink (Dublin Ice Tea)