I can only relate our experience from last year. The idea of a trip to Florida orignated with DH's long time wish to see a shuttle or rocket launch. We were orignally going to go during spring break, but the launch was postponed. We then re-scheduled for late July and booked the trip. Again, it was postponed, but was supposed to be a few days before the end of our trip. Again, it was postponed, and I don't think it actually launched until mid-August.
Basically, you're going to have to be flexible, and hopefully not terribly disappointed if it doesn't happen.