The actual trip won't take that long, depending on which park, but you can wait a significant amount of time for a bus. I've had the experience of waiting for a bus for one park and 3 show up for another park before the bus for my park comes. AKL is quite remote. Also Kidani gets picked up first (at least that's the case on my last stay there 2 years ago), so sometimes there's no seating by the time the bus gets to Jambo House. I would leave an hour if I'm going for a specific time, like an ADR. JMO