Disney Cruise Line Navigator App 

You can do many things on the Disney Cruise Line Navigator App like before you board you ship. You can Check in for your cruise, book Adults Dining, book Shore Excursions, Book Activities, book Mixology Classes and Spa Appointments.
When you're on board and connect to the ships Wi-Fi, you can check your dining Assembly station and check what's happening on your cruise.
You can download the app from the Apple Store or from Google Play. This app does everything for you, and I found it really useful to use on the ship and off the ship.
When it comes to check in, booking Adults Dining, Mixology Classes and Spa Appointments, they will become available 12am eastern time, so if you're from the UK, this will be 5 o'clock in the morning.
Hope you find this video useful, and if you have any questions, please put them in the comment section below.