Hi there, Lyndsy!
What a wonderful countdown to have!
You most certainly can pay down your balance with prepaid Visa cards. And if you booked your trip through the Walt Disney Travel Company, you can do so over time, or all at once either online, over the phone or in person..
When you check in to your Resort, you will be given a Key to the World. That becomes your one-stop pass for your room, your Park tickets (if you would like them added on), your spending account (if you wish to link a credit card to it), your Disney Dining Plan (if you purchase it). and your identification for fun benefits like
Extra Magic Hours.
You'll also receive, at that time, a welcome packet featuring information about your Resort, the Parks, and the Times Guides for the Parks, detailing all of the exciting events for the current week.
And once that's done? Go make magic!
See you later, celebrator,
-Deborah B.