I don't know how dynamic AUPs are - i.e. when they are released for sale, but they are limited and once sold they're sold. I once arrived to discover the person in front of me took the last one.

So while it doesn't take long to do, I'd be getting there on the early side to maximise my chances. That said, I'd also factor in the possibility of no AUPs on the day (which is quite common in my experience) and having to hang around at the airport for ages. So... if it were me, I'd get there at normal time but make a beeline straight for the ticket desk to ask and hope it's my lucky day.