There's no discount for Disney Visa cardholders; they do however offer 6 months interest-free financing on packages. In fact, if you make payments on the package, you get the interest-free financing on each payment as long as each payment is at least $101. If a discount is offered for your dates after you've booked, you can call and see if the discount can be applied, but there are a limited number of rooms available with any discount, so you might not be able to have it applied.