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Good age to start, he will probably be bored with everyday activities and need the extra stimulation, plus be ready for time away from you. He will have around a school year I suspect in nursery and as it is at the local school, assuming the school admissions policy means that you are highly likely to get a place, will move from the nursery to the reception class without any difficulty.
I've cared for several children who have gone to nursery for a few hours a week at nearly age 4, thus for the year prior to them entering school.