NZ doesn't have the same set system of school years as there is in France. And you will find that the subject matter and skills tackled will not be the same, necessarily, and if they appear, will not necessarily be taught in the same order as you have been used to seeing. When you approach a school wanting your child to start there, they will place him partly according to what you can tell them about him, and partly according to how they find he works - there is quite a bit of flexibility on the matter of chronological age.