The earliest that children could start is up to eight weeks before they turn 5.
Western Heights Primary School principal Brent Griffin said the bigger picture needed to be considered.
"It's not just a matter of letting children start school at 4. There will need to be space and teachers for these children.
"Our school currently has an enrolment scheme, so we don't actually have the physical space, but on top of that, there's a scarcity of teachers available in Rotorua."
Mr Griffin said the move would benefit some children, but not all.
"Certainly there are some children who are very ready for school at 4, but others really struggle to get to grips with school."
Otonga Rd Primary School principal Linda Woon said she was not against the idea, having taught in places where children were allowed to start at 4.
"Parents are the best ones to know whether their children are ready for school at 4 years old. There are pros and cons of the idea but I am keen to see parents making that call.
"What I am all for is children starting in cohorts at the start of each term because it is far less disruptive. There is a lot of value having all the children starting at the same time."
Readers on the Rotorua Daily Post Facebook page had varying opinions.
One wrote, "yes it sounds good. All four of my children are intelligent, independent, sporty and bilingual so it would be good to start school at age 4. They allow it in Australia [and] it has huge advantages".
However, others said they were against the move, saying 4 was too young to start children at school and if anything, the starting age should be increased to 6.
What's changing
- From next year school boards will be able to choose whether to change to a new "cohort" entry model, allowing children to start school at age 4.
- For school boards that opt to change to the new cohort option, students will start from the beginning of term closest to their fifth birthday.
- Parents will have the choice to start their child up to six weeks before their fifth birthday in term one, two and three, and up to eight weeks before their fifth birthday in term four.
- Families won't be legally required to send their child to school until their sixth birthday, as is currently the case.
- How many schools will take up the option is not known.