We just got back, and for what it is worth, I will share our strategy. We left the Royal Pacific at about 6:40 and walked over. Entered the park immediately and walked toward DA. Stood in line outside DA near Men in Black. Line started moving before 7:00. By the time we reached the entrance to Gringott's at about 7:10 the wait time posted was 180 minutes, yes you read that right, 3 hours. A friendly cast member pointed us to the single rider line (which I don't think had been open as long as the regular line), and suggested that the wait would be much shorter. Had the ride not broken down, we would have been on in about another half hour. HOWEVER, the ride DID break down, and we waited about an hour for it to come back up. It was about 8:15 when we got off the ride (which I really liked a lot, but I do think that FJ is a better ride). By the time we got off of the ride, the posted wait time was 300 minutes! So, my takeaways:
1) You can either spend your wait time in line outside the park, waiting for it to open, or inside the park. We preferred to sleep in a bit, and do our waiting inside.
2) Do not take a bag. Serious time will be wasted stowing your stuff in a locker. Leave the bag with someone who won't ride, or get a pay locker in another area of the park first. Or, cargo shorts!
3) Use the single rider line. Your wait will be much shorter, and unless you have small kids who would not be comfortable riding alone, it really doesn't matter if you are sitting next to family/friends for the short duration of the ride. You will miss the stuff in the queue, but I am not sure it would be worth the extra time.
4) Be prepared for the ride to break, and to have to either wait or abandon ship during the down times. If we had been in the regular line rather than the single rider line, we probably would not have wanted to add the extra hour to the already 2-3 hour long wait.
5) It might be better to use the early entrance to tour the area, shops and visit Ollivander's, then try the single rider line later in the day when the waits have dropped back down from the 300 minute to the 180 minute range.
6) Don't take the Hogwart's Express from IoA to US during the early entry hour. You will have to exit the train, walk all the way back to the front of US and stand in line again.
7) We thought the Hogwart's Express was actually a better experience than Gringott's, but don't try to take it around 3 or 4 in the afternoon, when lots of guests are switching parks. We had a 50 minute wait at that time, but only a 10 minute wait at about 10:00 a.m.
8) Breakfast in the Leaky Cauldron was good, but pricey. Make sure to take your
AAA card, if you have one for the 10% discount.
9) DA theming is amazing. Take the time to really look around.
Cheers!
& 
