Erica, welcome aboard! Congrats on the decision to take your boys on what is sure to be a vacation to remember forever! The good news is that you can absolutely make multiple payments to pay off your cruise vacation, and even extra payments toward your stateroom account so you have money on your account to spend onboard for special extras like Port Adventures!
What our family has always done was pay the deposit when we book our cruise and then pay a little every month leading up to the date that it must be paid in full, 75 days prior to setting sail. My secret is that I purchase Disney Gift Cards at our local grocery store, Kroger, because they offer double fuel rewards on gift card purchases, saving us money when we fill up our car! Sometimes they offer triple or even quadruple fuel rewards, so I think of it as a discount on the cruise. Really, it isn't, but I need to pay for the cruise and for gas for our car, so why not use Disney Gift Cards to pay for the cruise and save money on our fill-ups in the mean time, right?
I then call Disney Cruise Line's agents at 800-951-3532 each month to use my gift cards, or if you'd prefer, simply a debit or credit card, to put a certain amount toward our account. You can call as often as you'd like! So, make your own payment plan, Erica, and as long as it's paid off by the set sate, you'll be ready to go! After that, though, I do continue to pay more toward our onboard account so we can know we have money already there for spending onboard. You know you'll be finding at least one souvenir your boys must have! Plus, you can pre-pay the gratuities, so that helps too!
Another option is to check out the
Disney Vacation Account, which can be used toward Disney vacations, including with Disney Cruise Line. It is a relatively new program which helps guests save and plan for their next Disney trip! Have fun as you begin planning, Erica!