@1459WDW - There are a couple things to note that I'm not sure are mentioned in the FP thread or not. They may be, but just stuff I have noticed happening. Never cancel a FP. While it seems the polite and courteous thing to do, so others could use it, if you cancel it, you may not be able to book any more than 3 FPs for that day. I have personally had this happen. If you're not going to use a FP, just let the time pass, without canceling. It's horrible that the app behaves this way.
Also, if you have have "anytime" FPs put on your account for whatever reason, you will not be allowed to book further FPs, after the first 3, until these are used. It stinks because we wanted to save them for the next day, as they were good for two days, but couldn't book any new ones until they were used. These are usually put on your account as compensation for inconveniences that happen, such as your bands not unlocking your room, etc.