My son's school was straight in with everyone starting full time (9 to 3) on the first day. This seemed to suit the older ones but my then 4 years and 3 days old son really struggled physically, educationally and mentally. Up until the day before he started, he was still napping in the afternoon. It was ridiculous IMHO.
My oldest now 10 was the same at 4, still sleeping in the day - even though he did 4 full days at nursery and was the only child in his group. they made a special arrangement for him. Only 4 months later he started school but had just about given up his sleep then and so he managed find.