We actually did this on Wednesday and again on Saturday, so we're seasoned pros.

I'll tell you both of our experiences in a nutshell.
First Experience: April 6th.
We got to the MK at opening (8am) rode Buzz two times and went straight to Tangled, arriving at 8:30. We were the fourth family for the
10:15 show. My mom waited (she offered/insisted) and I rode some stuff in Frontierland.
The rest of your party must return about 20 minutes before your show, the CM emphasized that a LOT. I was the only "kid" above the age of 10 in there (I'm 17), but it was amazing. The kids danced and coloured and the characters were so interactive, even with me! I started talking to Flynn about his satchel and he showed me what was inside, after a heavy screening process also involving Blondie.

(Make sure to ask, it's very cool!)
Second Experience: Yesterday.
We were at Epcot in the AM and I wanted one more pic with Rapunzel and Flynn before we went home, so we headed over.
We arrived at about 1:30 and were about 8 families back for the 3:15 show. Rapunzel had "the same friend" and Flynn had "made a new friend", but Rapunzel was very good in helping Flynn remember my previous visit.
Overall, it's worth it, but GET THERE EARLY.

And bring an umbrella for shade.