Our experience is from two weeks ago. We picked up our FP right at park opening, so we got the first show. The FP said to show up at the dock area at 8:00 for the 9:00 show, but after talking to a few CM we realized we would need to show up a lot earlier. We got there a little before 7:15, and hung around waiting. We were eventually among the first let in to the "holding" area, which is the waiting area for the Columbia/Mark Twain. That was around 7:40. At 8:00 they let us into the viewing area...you are walked down as far as you can go in the viewing area by a CM. We were fortunate to get in a seated area. A lot of the regular FP is standing.
So my advice, which is based only on a one time experience, is get a FP first thing, they run out quickly, and go wait by the dock area early, and don't let the CM shoo you away, because they may try to tell you to come back later. Just hang around and don't do too far. Because you don't know when they will start letting people into the "holding" area.
Good luck!!