Some schools are preparing to end the system in which children start on their fifth birthday.
Cohort entry lets schools make new entrants start on the first day of each term rather than on the day they turn five.
The system is allowed to be used from the start of next year, but schools have to give at least one term's notice before they introduce it.
Children do not have to start school until they are six, but the earliest they can start at a cohort entry school will be the first day of term closest to their fifth birthday.
The Education Ministry said that meant some children might start school up to eight weeks before their birthday, while others will have to wait up to eight weeks.
In Whangarei, Onerahi School deputy principal Annmaree MacGregor said the system was in the best interests of the children.
"Some children are ready earlier than others and so what cohort entry can do is support parents to make the right choice for their own children instead of having to come at a particular time on a birthday," she said.
Mrs MacGregor said cohort entry would also make life easier for teachers.
"Having them all coming on the beginning of the term allows you do quite good induction.
"They're all getting the message at the same time about being school children and working together and the social and emotional needs that children have when they're transitioning to a new environment. It works quite well when you've got them in a little group."
Mrs MacGregor said most parents in the community supported the change.
At Kuratau School near Turangi, the principal, Craig McGregor, said cohort entry was a win-win situation for children and teachers.
"If you can enrol them as a group ... you assimilate them into the school as a whole group so the transition process is much better, they've got peers going through the same thing who can support them, so it's just a win for everyone," Mr McGregor said.
In the Waikato town of Cambridge, principal Hamish Fenemore said the main benefit was for school management, especially for bigger schools that had more than one new entrant class opening up during the year.
"Instead of scrambling around and crystal ball gazing and having to open classrooms in the middle of terms, it gives certainty to say, 'Well, here is the date that they're all starting therefore we can put in the staffing to meet that need.'"
Mr Fenemore said his school, Cambridge East, would not adopt cohort entry next year because it was already opening a new new entrant class every term.
Principals' Federation president Whetu Cormick said many schools were taking a wait-and-see approach to the option.
"We are hearing that some principals are consulting with their communities to look at this as an option going into 2018, but we're also hearing that many principals are watching with caution and looking to see what other early adopters are doing and whether or not it's going to be something they might consider beyond 2018," he said.
Mr Cormick said some principals were worried the rationale behind the change was administrative, rather than based on children's welfare.