Can't say for sure but i'd bet that they'll make it as difficult as possible for you mate.
Here's an example,
Worked with a guy from the UK in 07, he had his qualifications assesed,got in the country on those qualifications and had a job. Took his plumbing theory paper and passed, they then told him he wasn't eligible to sit the exam as he hadn't done enough hours even though they had told him he could do the exam. He argued with them for over 2 years and finally got his local MP involved, one letter from the MP and the following week they tell him that his exam now is accepted and that he can do his practical down in Wellington.
Bid difference now is that he has to pay out approx $5,000.00 to do his practical yet at the time he passed his theory he could of done his practical in Hamilton for less than a grand.
Hope it all works out well for you but i'm yet to meet or hear about someone who they don't screw over.