Christmas in the Caribbean!!

Finally got everything confirmed: I'm going back on the Spirit for Christmas.
I'm going a cruise later than the other seasonals because of my exam (I'm writing the exam the night before I leave). I'll be doing the same run as I did at Thanksgiving, plus a 7 day cruise that'll take me to 3 countries/territories that I haven't been to yet - Bahamas, USVI, and Peurto Rico. I'll surpass my age in countries/territories!!!
I'm a bit confused about my sign off date ... my flight out of Miami is on the 4th, a Tuesday. The ship will be in Grand Caymens then. I'm hoping that I sign off on the 2nd, and that they couldn't get me a flight (busy time) until the 4th. That means I'll get to stay in Miami for 2 nights(for free) - how great would that be??? Cross your fingers for me :)
Merry Christmas to me!!