check with EI what time checkin opens for the flight. I am guessing that they open at 5, so aim to be at the check in between 5 & 5:30, that gives you 90 minutes then to get through, which is what DAA are recommending at the moment!
If you're planning to drive to the airport and park in the long term, allow some extra time for that as well, the buses are not as frequent that early, and tend to get full as well.
Sounds crazy I know, but there are a lot of flights out that time of the morning, so there's always pressure on the gates.
Hope that helps