There is no time limit
per se, since a Permanent Resident Visa is valid indefinitely. However, you should be aware that the grant of an Australian Resident Visa on arrival may trigger the cancellation of your Permanent Resident Visa, under section
64(1)(f) of the Immigration Act 2009: to avoid this, you would need to transfer your Permanent Resident Visa to your Australian passport.
Ultimately though, this will make no difference if you choose to return to New Zealand in the future, with regards to the length of time it will take to meet the
presence requirement for New Zealand citizenship by grant. You must be present in New Zealand for a prescribed time in the five years preceding your application for New Zealand citizenship, and your absence from New Zealand has almost certainly completely undone all past progress towards meeting this requirement.