If it were me, and it is many times, I would leave MK 90 mins before your pickup time. If you leave an hour before, this is the time the buses will run slowly, and you'll just miss a bus, having to now wait 20 mins for the next one. And that one will be delayed for some reason. Then, once you get back to AKL, you're going to want to use the restrooms, gather your belongings, and arrive at the DME bus stop about 15 mins before your pickup time. The time you are given is NOT the time you should be arriving at the bus stop..it's the time the bus is due to depart the resort.
If you have a 4:30 p/u time, I would plan on leaving MK no later than 3, maybe a bit before.