As more EVs arrive in NZ, the demand for chargers will increase, and that demand will be met. We are already seeing a surge of new chargers being deployed and as more people move to EVs there will more and more added. Until there are more chargers than petrol stations - I am sure I read recently that this has already happened in Japan - i.e. chargers > petrol stations.
So I think your concern re. wait times will probably be fairly minimal.