It depends on your commitment, the availability of Aircraft (& instructors) at your chosen flight training school or aeroclub, and if you're self-funded (no HACS or Student Loan scheme) the size of your wallet... plus all the paper work that was mentioned previously...
Best to ask around at the flying schools & aeroclubs to see what types of responses you get, but make sure they answer all the questions, many will promise you that you'll get it done in no time, but in many cases people are still there weeks or months later due to the weather being awful, instructors too busy or planes unavailable because there are too many students or because the planes are in and out of maintenance.
If you're in NZ, have a look at NZ as well as Australia and see how timings & price compare, and when you hear the stories of people who went from the flight training school to a B747 within 3 years, be very cautious.
Unfortunately going from NZ PPL to Aussie PPL isn't just an exercise in paperwork, but you'll find more about that on the CAA or CASA websites.
Good luck & PM me if you want to find out more about some of the options in NZ.