Hey I think its better to fly out of nz before your visa expires, maybe australia for a couple of weeks and then fly back to nz for 3 months. Well this is what I did and didnt have any problems. I had all my tickets booked before entering australia (from nz to aus, aus to nz and nz to home!) and had bankstatements printed so I had proof that I was there for a holiday and could support myself. (I'm from a visa waiver country so didnt have to apply for a visa as a tourist) this is only my experience I had a good read on inz website, emailed and called immigration because I wanted to be sure if this was okay and then I planned the dates and booked my flights. But I think it is beste you call them and email them as every situation is different.