Yeah, probably nearer 4 than 3, knowing how these things pan out and it's quite a packed card, but keep the tele on just in case.
I wouldn't think before 4am at the very earliest. Unless all the undercard fights are 1st round KO's! Everytime i've got up for a fight its been 4.30am ish and if the fight goes the distance and interviews i've been getting back to bed not long before 6am!
HBO start 4am UK time, i don't think they are showing any under card fights so fight will start 4:15-4-30