When we were there in October, the SDD line quickly ballooned once the park was open. We were there more than one morning during our trip. The longest times of the day we saw were probably from around 9:20 to 10:30. We saw it at 180 minutes. We were not there at high crowd times. I would either go there first and then to RNR and TOT, or I would try to do it around closing. The shortest line we saw for SDD was 60 minutes and most of the day it was between 90 and 120 minutes. Also, once you get your 3 FP done in the park (with one of those being a tier one)you can attempt to get a 4th FP+ for it. The best way to try it when one doesn't come up when you check is to book anything you can (I try to book one towards the end of the day since I don't plan to use that one) and then to keep trying to refresh and modify it to move it to SDD. I had luck doing that with FOP at AK. I did not have luck doing it with SDD although I tried, but I did pick up an Alien Saucers that way. Part of that depends on how big your party is-- there were only 3 of us-- so it was probably easier for us to pick some things up.