I was just reading old threads on this yesterday. In my contingency plan (yes, I make contingency plans lol) I have a second CP booked at 8:25, also the earliest I could get that day, and I wondered the same thing. What I read was that if you check in early there's a good chance you'll be seated early. One poster said they were seated at 8:15ish and were done and out in an hour.
I will keep trying for an earlier time but I don't feel like 8:25 is a dealbreaker either. People love to cancel this one the night before so there's a chance you could snag an earlier time even that late in the game.
ETA: my sister likes to throw curveballs into my plans if anyone wondered why on earth I need two itineraries.