Last month, the median house price for Northland was $298,700, according to Real Estate Institute of New Zealand (REINZ) figures. Based on that figure, first home buyers in Northland would need a deposit of at least $59,740 under the new lending restrictions.
The national median house price was $385,000, meaning a minimum deposit of at least $77,000 would be needed.
Mr Peterson said he worked with a lot of first home buyers, and while the phone was not "ringing off the hook" so far, he anticipated more people would try to get mortgage pre-approvals before the restrictions kicked in.
He expected to see many Northland house hunters chipping in together to purchase properties, or enlisting family financial help. However, he cautioned buyers against making panic purchases.
"People have just got to sit down and make a plan.
"It's tough but it could have been worse - the Reserve Bank could have put interest rates up too."
REINZ is cautioning first home buyers against rushing to purchase a property that might not suit their needs.
"It would be really unfortunate if people felt that they had to prioritise timing over prudence," said chief executive Helen O'Sullivan.
"I would still counsel people [that] it's better to miss out ... than get yourself into a pickle.
"It's a real issue at the moment. The reality is if you're a vendor and you've got a property to sell, purchasers are lining up ... and that sometimes mean it's a bit of a race."
Ms O'Sullivan said there were indications of increased activity last month by people looking to buy their first home.
A big concern for the Reserve Bank would be whether first home buyers sought out non-bank lenders which were not subject to the same lending restrictions.
"That potentially pushes risky lending into an unsupervised, unmonitored portion of the market."
HSBC economists Paul Bloxham and Adam Richardson said "a booming housing market" along with other factors, including the Christchurch rebuild, would force the Reserve Bank to lift interest rates, possibly by the end of the year.
- Additional reporting NZ Herald