If this helps you at all, I watched the
MDE times this morning (5/27: 7 a.m. EMH at Animal Kingdom) and made notes as they changed. I watched from about 6:30 a.m. to 8:30 a.m., and saw the app update as rides were added and as posted wait times changed. Below I attached a screengrab of my notes. This should be accurate to within a minute of when each posted wait time changed on MDE (I can't speak to the accuracy of the posted wait times themselves). "TC" means "temporarily closed."
You can get more "Observed Wait Times" from previous 7 a.m.-EMH days on Touring Plans — but the data they post begins a few minutes after 7 a.m. each day, which doesn't show Pandora rides right at EMH rope drop (around 6:40 a.m. today). I have looked through previous 7 a.m.-EMH days on Touring Plans just to get a general idea of the range of possibilities on those mornings. The 7:00-7:30 Avatar FOP wait times on MDE this morning appear relatively high, but within the range I've seen in Touring Plans' historical data. Based on that, I'd guess the pre-7 a.m. MDE times today are not too abnormal? From 7:30-8:30, the MDE times today are pretty average, if not kind of low, compared to those previously-observed times on TP.
(I can't say with certainty whether MDE times compare to whatever TP is using for "Observed Wait Times" on its charts. FWIW, when I've previously noted MDE posted times, they have ended up being pretty consistent with TP's "Observed Wait Times." TP also occasionally includes "Disney posted wait times" in their charts, and they are usually in line with their own Observed Wait Time points. On Tuesday morning, Touring Plans will post their records for today's lines, and then I'll be able to check how similar they are to what I recorded this morning from MDE.)
Obviously none of this is perfect and may end up being not at all predictive of the conditions we find on the mornings we visit. These 7 a.m. EMHs at AK don't have a ton of precedent from which to collect information, and I've found very little anecdata from visitors who previously did 7 a.m. EMHs at AK. Like I said, I'm just looking at whatever data is out there, so I can have SOME idea of a range of possibilities to anticipate and make semi-informed decisions.
I can't share TP data directly because it's password-protected for subscribers. But from other free, public sources I can tell you these are the 7 a.m. EMH days I'm aware of from the past year:
5/27/19
5/25/19
4/27/19
2/16/19
1/5/19
1/2/19
12/29/18
12/24/18
11/24/18
11/19/18
8/18/18
8/11/18
In general, the times appear to stay shorter for a bit longer on 7 a.m. EMH days than on 8 a.m. EMH days. But even on 7 a.m. EMH days, Na'Vi and FOP (and frequently Kilimanjaro Safari) have quickly gotten longer than I'd want to wait.