We went to MK 3 days last week. The new PP queue is well worth it to see at least once, and the best time to do it is at RD. We stopped to take pictures and arrived at PP at 9:05 and had an 8 minute wait, enough time to enjoy the queue. If you don't RD PP, I would definitely use a FP on it.
We had a 7 year old girl in our group who's 2nd favorite movie is Little Mermaid (behind Frozen of course). We rode the Little Mermaid ride 5 times. In the afternoon on a moderately busy Saturday, the posted wait time was 40 minutes. I timed it, and we actually waited 11 minutes. Every other time we rode it, the posted wait time was 20 minutes, and we walked on with no wait at all. There are much better options to use one of your FPs on.
The day we did RD for PP, we had FPs for 7DMT, ETWB, and A&E. Another day we had FPs for 7DMT, PP, and Pooh. All of these FPs were well worth it, as all of these were posted 40 minute waits or more when we used these FPs.
As other posts have said, change the FP time of Little Mermaid ride to any other time, and then adjust the FP time of PP, and then make additional changes from there.