Yes, by 7:30 (or earlier) as Robo said, is when you want to arrive for any PPO breakfast. They will not let people into the park until 7:45-7:50. So depending how close you want to be to the front of the pack, you might want to arrive earlier.
In late July (YMMV if you go at a busier time) we arrived about 7:30 and thought the timing was perfect. We weren't at the front, but when they let everyone in at about 7:45, we didn't feel too far back in the crowd. In fact, we were second to arrive at BOG that morning. Our ADR time was 8:25, I think, and no one told us we had to wait for that precise time. We got there before they were even officially open so sat outside for a few minutes. The two things that helped us get there so fast were first, we didn't stop for photos (we had done that the previous morning). And second, we are fast walkers. We find the sidewalks (use the one on the left) less crowded and faster moving.