Hi Kerrie!
You're in for a treat! The Disney Magic is a wonderful ship and the Eastern Caribbean itinerary is great! I'll have to admit that I'm just a tad bit jealous!
While itineraries can vary, the Eastern Itinerary often starts with two days at sea before port stops begin. This means you'll have lots of time to get into the relaxation mode. You'll also have lots of time for the your 9 year old to start enjoying the kids clubs - you may have trouble getting them to hang out with you!
Typically, the first days have movies, shows, tours and adult activities in the night clubs. Personally, I always keep an eye out for the tours of the ship's galley. Its one of my favorite "behind the scenes" things to do!
Don't forget to keep an eye out for the Characters too! You'll want to catch a photo or two with them!
Full listings of the each day's activities will be delivered via the Navigator. Each night, your cabin steward will leave the pamphlet in your room. Hint: be sure to bring a highlighter with you to make sure you can highlight your next day's activities. We like to bring different colors for each member of the family!
Once the port calls start, you'll have a ton of options for excursions and self-tours. Disney Cruise Mom Andi suggests some great excursions in this
answer.
Hope you have a Magic-al trip!