Longest: an hour. It was MDA/caffeine though, which might explain it. I tend not to eat dinner when i'm gonna roll, to keep the come-ups faster.
Shortest: literally 10 minutes. And it was the fastest come-up too... off of a white butterfly. I sat up and was like, hm, i feel a little dizzy, and then someone who was looking at my eyes said my pupils literally just flashed open and i was rolling within 15 seconds. Thats the best kind.