Our kiddo's pirate makeover took about 25 minutes or so.
How old is your kiddo? Mine is 9 (almost 10) and in October we were back on board by 3, tired out. We did snorkeling, some other swimming, walking around, lunch, a bike ride, some turns on pelican plunge, and then hit the gift shop. All aboard was 4 anyway IIRC, but we wouldn't have been able to make it until then.
I'd go with the 3pm; it's really very elaborate and awesome, and would be a shame not to get a bit more time out of the look. The Captain Jack on our cruise was also fantastic with the kids who came to meet him in costume.