We did both RD and FP+, so either is possible. I would get the FP+ for later in the day as previous poster suggested. Not only will you maximize other opportunities, but the ride was down three times that affected us last week - too darn bad if you are SB, but the one time that it was down when we had a FP+ the FP+ system automatically converted our FP+s for 7DMT to a now-until-park-closing FP+ for any of about 8 options including 7DMT if it came back up. (It came back up and we rode 7DMT, but it was nice to know that if it had remained down, we could ride SplashMtn or Barnstormer or something else instead. We did notice that SpaceMtn and BTMRR were not options offered. SplashMtn had longest SB line at the time, so I can't figure out the logic of what was and was not offered...)