@Primadonna thank you for your reply.
I am Greek, my wife Cypriot so no Dutch background. We don't have an issue with our son missing a year. We prefer him to be properly prepared for the evaluation regarding higher Education. The thing is that we want first to be 100% sure that we can live in the Netherlands before moving there. So the plan is for me to go alone for 6-12 months and then the rest of the family follows.