As already noted, the early opening and ride operation in Pandora have been a daily thing since it opened nearly 2 years ago. The timing is not consistent (I've experienced early openings anywhere from 10-45 minutes before official park opening times), but I haven't been held until the "official" opening in the last couple of years over many visits in all different months. A lot of guests are not aware of this and are surprised by long standby lines already waiting for them in Pandora right at "opening" (just as many other guests are aware of the early opening - as evidenced by how many people get there 1+ hour before official opening). Just this week, we were let in almost 50 minutes early - exiting Pandora just before 9am I saw a group of just-arrived guests sprinting across the bridge and the leader yelling for everyone to hurry as there was hardly anyone in front of them yet (sadly unaware of the 2+hour line waiting just down the path).
Fun fact: you can RD the park twice in the same morning - since the other lands usually don't open along with Pandora, it's possible to RD for one of the rides there, get off that ride and (if it's still early enough) head to one of the bridges for Africa, Asia or Dinoland, where you'll be held for your second RD.