Since you don't get in until 3:00pm (or later, if that is when the flight comes in), just go to the RIU Negril and rest up and eat. No reason to head out until after 9pm. Maybe you can contact one of the drivers on the board or one outside the resort to take you down to Alfreds and pick you up when you are ready to come back. Prices go up a little so keep that in mind when getting a price. Getting down to Alfreds won't be that hard but getting a ride back just may be.
Enjoy yourself. Lots of room around there to recreate.
Peace and Guidance