We have been there twice in the past week (and going again tomorrow). The lines are bad pretty much from open to close.
The line for Flight of Passage has been going up over an hour within about 30 minutes of park opening. We were at rope drop for morning EMH a couple days ago and immediately went to Flight. We waited about 5 minutes, but by the time we were out of the ride (8:20am on a 9am regular opening day), the line was over an hour. It stayed at an hour and a half pretty consistently all day and evening. We were in Pandora right before the 9:15pm Rivers of Light and the wait was close to 2 hours at that time. So...make that one your FP+ if you can get it.
The Na'vi River Journey is not quite so bad. It stayed at about 30 minutes wait from EMH opening through regular opening. It went up around an hour just after regular opening and stayed between 40 minutes and an hour all day. It was still an hour when we went to Rivers of Light.
The other day we were in AK, we were there to do the evening activities. Pandora looks amazing at night, but if you haven't been during the day it can be a little tough to figure out your way around. We were there during evening EMH (and then the Pandora extra late extra EMH) and the lines for both were still over an hour the whole time.
So, I'd recommend getting to AK before rope drop and going to Pandora right away and try to do Flight and the River Journey back to back. Then just walk around a bit to get a feel for the place. Have evening FP+ for Flight (I think you will want to do it twice...it's like Soarin' on massive steroids) and go back through Pandora after dark for the amazing visuals.