Originally Posted by Thai-Kiwi

I recall asking this a few years back at the premium checkin as we were about to fly WLG-AKL-SIN-BKK and had arrived at 4:45am in the hope of getting through security bang on 5am and into some brekkie a few minutes after 5am.

The checkin agent said they had some flexibility as it was mostly around getting 'ducks in a row' for the AKL-SIN departure (in our case). It'd be good to know the actual rules/policy, rather than a blanket "2 hours before" or whatever is stated.