When I used the new system in June, security (your first stop after checkin) opened almost right at 0430L and with GE/Nexus was through in a matter of minutes. I arrived at the airport at 0415L.
The thing to remember about the AC MLL is that although the lounge is "supposed" to open at 0445, the elevator will only operate once it's activated. You can call for it to go up, but until the button works, the lounge is closed. Enjoy the ride between 2nd and 3rd floor a few times until it finally will let you go up to the 4th.
@Toddcan there is NO reason to show up at 3am..... 4am is plenty since you can't do anything until at least 430am anyhow.