When the parks reopen, the waits are unknown at this time.
Previously, if you weren't in line, meaning at the tapstyles, about an hour before official opening, or EMH in this case, you were waiting a long time.
Last October, we arrived 60 minutes prior to EMH. Got in the park 30 mintues before opening and were held at the bridge to Pandora. Had about a 10 minute wait to get on the ride. When we came out, the wait was 90 minutes. If you arrive at 7:45, expect at least an hour wait, probably more.