You can check you bags in early but not sure how much time you will have for sightseeing. Maybe 90 minutes. By the time you claim your luggage, find a cab, and get to the pier it may well be 10:30.
Keep in mind they may very well start boarding at 11:30 and everyone needs to be checked in 2 hours before departure and onboard no later then 3:00 for a 4:00 departure.
Arrival at the Cruise Terminal:
For your comfort and convenience, we recommend that guests who have not completed their Online Check-In arrive at the cruise terminal no later than two (2) hours prior to the scheduled embarkation time printed on your cruise documents. Guests who have completed their Online Check-In should arrive at the terminal no later than one (1) hour prior to the scheduled embarkation time printed on your cruise documents. We STRONGLY recommend guests complete their Online Check-In at least four (4) days prior to sailing.
Final Boarding Time:
In order to facilitate the embarkation process and the processing of your eDocs, and to comply with new government regulations governing departure manifest, all guests are required to complete Online Check-In at least one day prior to sailing and must complete check-in at the cruise terminal and be onboard the ship no later than one hour prior to the departure time noted on their cruise documents or they will not be permitted to sail. Please note guests who have not filled out their Online Check-In must arrive at port two (2) hours prior to sailing. Any late arriving guest may join the ship at an approved port of call in the scheduled itinerary. Such guest will be responsible for all applicable fees and travel expenses to that subsequent port of call.