We arrived at the park at around 7:40 am, and there were already pretty good-sized lines at the turnstiles (probably 30 or so people deep at every turnstile). We got behind a few folks in the short line that said it was closed, but it was pretty clear that the family in front were talking to the CM standing there and she was confirming it would open when the others did (thanks DisBoards for the tip to keep an eye on those "closed" or "breakfast only" entrances that transform to regular entrances at rope drop).
So, they started letting people through the turnstiles maybe 7:50 or so, and we went left where they were directing people for Jedi Training sign-ups. The line was not too far down the first street on the left as you enter. We didn't run or anything, and a few folks were walking super quick and ended up in front of us, so we were maybe 5th or 6th in line. The CM's started writing down names, and then as soon as the park officially opened at 8, they started walking toward Sounds Dangerous and we all followed in a line. So we were signed up and ready to go by about 8:10 am.
I'm not sure how quickly they filled up the shows, but I might consider having everyone in line well before rope drop and trying to be one of the first few people in line to sign up, and then you might still be able to be over at the restaurant by 8:05 or so--we usually end up waiting a few minutes to be seated for character meals, so I'm not sure, but would being just a few minutes late be a huge deal?
DH participated in the TSM stampede, walking quickly but not trying to be first or anything, and he got FP's for about 8:55 I think--standby line was already 25 min. when we got over there from Jedi sign-ups. When we got off after our first ride at about 9 am, the FP time was about 3:45 pm so we got more FP's and were able to ride it twice that day!