We had 5:50PM reservations for Liberty Tree Tavern before our Princess and Pirate Party in March. We got done with dinner at 7PM just in time for the party but we only had about an 90 minutes to go do the rides before the 8:30PM parade. My son was really into finding the treasure spots and he found them all during that time frame.We had a great time before the HEAVY rain that night. We ended up leaving early due to the weather otherwise we would have had a blast riding all night long.
If I had to plan it all over again. I would have had a early dinner at 4PM/5PM just so we had more time to play early in the evening before the parade.
Eating at the castle is a special treat, so if you haven't done this before and you can't get another day/time then that will add to your special night.
You will have a great time either way.