It depends.
At the Deluxe and Moderate resorts, Bell Services runs 24 hours a day and will deliver bags if they arrive in the middle of the night unless you make arrangements to have them held (and even sometimes if you do). At the Values, Luggage Services close at midnight and in most cases bags arriving after that won't be delivered until morning.
For an 8:30 p.m. arrival, you should be at AKL by 10 and checked in by 10:30, so tagged bags should be delivered to your room by 1 or 1:30 a.m. If you want them delivered that late, just go to your room and wait (or go to bed and hope the knock on the door wakes you up). If you want to use the DME luggage service but don't want your bags delivered in the middle of the night, ask the front desk to notify bell services that you want your bags held AND put your Do Not Disturb sign out on your door in case the message doesn't get through. In the morning you can call as soon as you wake up and your bags should arrive within a few minutes.
If your flight arrives after 10 p.m. (even if it was scheduled to arrive earlier) you have to go to baggage claim, collect your bags and take them to the bus. If you just don't want to wait at your resort for your bags, leave off the DME tags, go to baggage claim, collect your bags and schlepp them to the bus. In both cases the driver will put them under the bus and unload them for you at your resort. A tip of $1-2 per bag is customary if you have the drive stow them under the bus for the trip.