AC38 departs MEL at 11:40 am, and is the only AC departing flight of the day. Checking bags, so can't do online check-in to get through security. Don't want to show up too early and wait landside at the check-in counters.

I know the check-in counter is open at least 2 hours before flight time, but is it possibly longer?

Asking for a friend with Prestige 25k status, that wants to maximize their time in the Marhaba contract lounge that they've already paid for. It's a long flight in economy to Vancouver...