They say it takes 30-45 minutes depending on which package you book. I would make your reservation at least 90 minutes before your dinner. That way you have time to take some pictures after.
I would schedule it for as early as possible. some poeple have reported then being over an hour late in their schedule. Plus what princess doesn't want to look like a princess all day lOL
Be sure to do it early. I made my adr for crt at the 180 day mark, but called last week for BBB and they only had an apt in Downtown Disney, which seems like it will be a hassle. We are going in September, I didn't realize BBB fills up that fast!
I booked bbb in MK about 150 days out and there was only one time available at 11:40. I've been calling every few days to change it to an earlier time with no luck. It's a pain to call because you have to listen to such a long recorded message first from the Fairy Godmother. The first time was cute, but it got old fast.
We are doing BBB at 1pm, then dinner at 1900 at 430, followed by the halloween party after that. I wanted to spread it out so there was no rushing, that's the day we're looking forward to the most so I wanted it to be as hassel free as possible.
We did lunch but did BBB first thing in the morning 8am park opened at 9 we were done 8:55, got in the park early and was right there to be the first on Dumbo. Then the kids enjoyed the attention all day! My appt may have started a few minutes before 8 and I had two girls.