We had an 8:30 BOG reservation a few days ago, but showed up at 7:35. They let us in with everyone else with PPO ADRs at 7:45 and we were the second group to check in at BOG around 7:55. After check in we waited just outside the castle doors until around 7:59, when a flock of CMs came out to clap as the doors opened and we entered. We had ordered in advance online, so just needed to pay at the kiosk and take our seat. We claimed our preferred table, got our drinks, and our food arrived almost immediately. We ate and then went to line up for 7DMT (we were behind only 2 other people) and ended up being on the first train of the day when the park opened at 9.
So, long story short, if you have a PPO BOG ADR get through the taps before 7:45, enter the park whenever they open for PPO ADR guests, and proceed directly to BOG. They will let you in immediately, regardless of your specific reservation time. Ordering in advance will also save you time inside. Enjoy!