Additionally, you could also take the launch from WL to the MK and then the bus from the MK to AKL.
Or you could take the bus from the WL to DTD and then the bus from DTD to WL, but I would recommend against this. I think it took us about 45 minutes to get from WL to DTD.
Or, based on the timeline you presented, you might want to go directly from the airport to AKL or get a taxi directly from WL to AKL. I not sure you'll have enough time to get from the airport to WL to AKL or if you do, it might be cutting it a little close.