Was in WDW from February 16th - Feb 22nd. Here is how we used it:
1) We always make our 3 initial FP at the 60 day mark
2) With the exception of Wednesday(Epcot day), our days in the park start between 11-1. We have our first 3 FP done by 4-5pm.
3) I was able to book Splash Mountain, Big Thunder, Space Mountain, Peter Pan, Soarin, Test Track, Toy Story Mania, RnR, Tower, and Frozen ever after.
4) As soon as I tapped the turnstile on the 3rd FP I would start hunting for the next. I would grab whatever time was available and keep refreshing to move up.
5) On multiple occasions I grabbed FP that conflicted with other plans. I would go to the CM at the ride and speak very nicely to them asking to use my FP earlier. Every CM allowed us to do so, with the exception of 7 dwarves mine train.
The system works great, as long as you keep your expectations in check. It will be very TOUGH to get FOP, 7DMT, and SDD, though not imposible. You really need to be persistent. Understand that you will have your face in your phone for quite sometime trying to get the FP you want. The earlier you start using up your first 3 FP, the better your chances. MK is by far the best park to use this system.