Having been through too many "exceptions" at comps, you should NOT need to ask if you can set up earlier than the posted times. EVERY paying entrant should be informed of that, perhaps with a time restriction.
As of now, it's just total BS . . . Please define who's so much more "special".
If everyone is not notified of the opportunity to arrive when it bests suits their schedule, it automatically creates an unfair advantage and a sense of entitlement.