I'm assuming you're going to be parking the car (or at least paying for parking) then an hour beforehand, or 45 minutes-ish? If that's the case, from my experience the crowd is typically not that bad prior to opening, especially if you're doing it prior to EE, as typically that is what I used to do, however it's been a couple of years for me so it might be different, so someone else might be better to judge. However, for me, it didn't seem to get crowded and claustrophobic to me until it was after opening.
Also, I typically do not do the bag line, but the few times I did, it would take about 10-15 minutes, but might be busier if it's May. However, like I said if you arrive that early, you'll probably not really wait at all.