Congrats - sounds like fun! .... As far as planning, don't worry about the short amount of time. Just plan your transport to and from the ship, and maybe pick your excursions, and don't worry about the rest. Just leave it unplanned. On such a short voyage, things are more or less planned for you, with each full day in a port, and evening shows and dinner at pre-arranged times without needing reservations. Just enjoy!