Welcome back, Carrie!
When your window opens for online check-in, simply
log in to your reservation on Disneycruise.com. Here, you can view one of a number of options. The two you should begin with are "My Cruise Activities" and "My Online Check-In". You can also begin to register your children for the Oceaneer Club and Lab.
"My Cruise Activities" is where you'll view each day of your cruise and be able to add activities, such as Port Adventures, Adult Exclusive Dining, and Spa Treatments. There you can choose the time that's best for you, if more than one option is available on each day for these extras. It's a good idea to have a plan right how of which activities you'd like so that when it's your turn to book, you can do so right away. Reservations at the Adult Exclusive restaurants and some Port Adventures do fill up quickly.
You can also begin filling out your Online Check-In documents as well. Under this tab, you'll be able to fill out your guest information, identification information, pre- and post-cruise information, as well as put a credit card on file for your onboard account and choose your port arrival time. At the end of your Online Check-in, you can print out the forms to bring with you to the port. Then, you're all set! Just start counting (or keep counting, because I bet you've already got a cruise countdown going!) the days until you set sail!
While you're checking in, don't forget that in this same area of the website, you can schedule a free character call. My kids love when their favorite Disney character calls them at home to say they're excited to see the kids soon on the cruise!
Good luck completing your check-in, and I hope you're able to book all the extras you're hoping for!