As
@eliseisawkward said, it's a short amount of time. I think the actual experience was about 10 minutes, but when you arrive for your appointment, I'd say I waited around 10-15 minutes before going in? So I think the 30 mins mentioned is fairly accurate. Also as mentioned, you have a two hour window so don't worry about moving your appointment.
When I got into the park for a 7 a.m. opening, I got BG 15 and was called while still in line for Smuggler's, probably at about 7:15/20. Even then I think I got out of SR around 7:30/45 (Had to walk from rope drop and then through the SR queue) and wandered around a bit before I headed to RoTR. I don't think I ended up walking on until 8:30 and was let in without any issue.