Hi there, Lynn!
This sounds familiar. My family's first Disney Cruise Line vacation was also paid for completely using Disney Gift Cards. Even with multiple staterooms to accommodate our large family, we made it work out well. Over the years, using Disney Gift Cards to pay for Disney cruises has only become easier.
As with Walt Disney World Resort theme park ticket purchases, the Disney Cruise Line Plan A Cruise portal accepts up to one Disney Gift Card per booking transaction. After you pay the initial deposit, you are welcome to pay off the cruise balance at your own pace. Since you already have Disney Gift Cards ready for incremental payments, you can simply enter each one at your convenience up until your reservation's paid-in-full date.
Tony's Tip: If you happen to choose a longer cruise itinerary or a higher category of staterooms that require an initial deposit larger than the maximum value a single Disney Gift Card can hold, there may be a couple of options to allow you to still use only gift cards for the deposit. One option is to request a courtesy hold on your reservation for as many as three days. Before the hold period expires, simply call the Disney Cruise Line to speak with a Cast Member who can assist you in paying with multiple gift cards. Or you may choose to break up your stateroom reservations into multiple transactions. Then, be sure to call Disney Cruise Line to request that they be linked together.
Tony's Tip Times Two: I recommend using a different Disney Gift Card for each payment on your cruise reservation balance rather than transferring funds to one or a few cards to reuse them for multiple payments. If for some unexpected reason, you need to have your reservations canceled, any refunds of cruise fares will be returned to the original forms of payment. Given the $1000 maximum value of a Disney Gift Card, having separate gift cards for transactions will ensure that they each have enough capacity to accept any refunds. I keep a note on my phone with all of my Disney Gift Card information for each cruise reservation, including the gift card account numbers and their corresponding extended account numbers (EANs). Even if you don't expect to need to cancel, there are sometimes cases when port fees for any given destination on your itinerary are reduced, resulting in a possible partial refund.
Tony's Tip Turned Triplet: You can even use Disney Gift Cards to pay for your onboard account. Most Guests opt to link a credit card to their onboard accounts for convenient settlement by the end of the cruise. Even though I usually do that too, I also prepay gratuities from the My Reservations page as well as use the Onboard Gifts and Amenities site to prepay general onboard credit. If our Port Adventures, onboard shopping, and other onboard purchases happen to be more than originally planned, I can monitor our onboard account in the Disney Cruise Line Navigator app and stop by the Guest Services Desk to make additional payments with a Disney Gift Card if necessary.
I hope that helps with your budgeting and planning, Lynn. Be sure to stop by planDisney with any more questions you may have.
Happy sailing!
~Tony