Sometimes, Disney guests will find a "bouneback" offer in their resort room. Most times, the flyer looks like a big pocket watch and it has specific dates on it that you can "bounceback" at a discount. The pocketwatch flyer will have a telephone number to call. You must book the bounceback before you leave your resort.
Hope this helps, Lisa
so I'm assuming if you have to book prior to leaving the resort, then you have to pay for it at that time.