Normally, if you submit all the proof of skilled employment, and include what shows that you have been working in the job for three months or more, you will be given your visa without any conditions on it. We have seen cases where the applicant didn't prove length of time up front and got granted their Residence with the Section 49(1) condition, but that was down to lack of their paperwork and could be sorted out.
So you probably could put in your resignation the next day as far as INZ is concerned, but it would also depend on what is in your contract with your employer, and also a bit of caution on your own behalf - don't forget NZ is a small population, and employers with the same kind of business tend to know one another, so it's worth trying to make sure nobody gets left with hard feelings, since the word can go round very fast.