I can’t speak as a parent but i agree with Ruby and Sharon totally. He’ll probably be terrified himself first day there and possibly sob his heart out but in the same vein he’ll also cry when you arrive to pick him up as he has had such a good time! I see it all the time…
He’ll be unsure of what to expect, just as you are, but if you sit down together with a good book about starting school/nursery it may possibly help. Some nurseries expect you to visit before the big day and if you are anxious i’m sure you could call the centre to see if they can answer any questions you may have – they will only be too willing to help. Most places are well trained in helping parents who are more nervous than their child!
I’m not a mum but have worked on the other side of the fence for a few years. I’ve had pushy/nervous/loud/quiet/relaxed parents and i can tell you i know for a fact that they will be able to help you as well as your child!
He will thank you in the long run for the social side of things.
I hope it goes well AW! 8)