To not know how to discipline my 4 year old

[Waltzered]

My 4 year old is great except when walking to/ home from school. He runs ahead to try and get with his friends, doesn't listen to me, won't leave the playground when I ask. I'm really embarrassed because it's always in front of other parents who have well behaved kids! He screams at me when I tell him off, and says he doesn't care about any punishments I threaten him with. (Time out/ losing toy for the day when we get home if doesn't listen).

I'm at a real loss as what to do. He's always been so well behaved up until starting school. I've never really had to tell him off.

First term at school they’re hyperactive but also tired and hungry. When you pick him up from school take an apple for him. If he eats it he doesn’t have to hold your hand BUT he is absolutely not allowed to cross any roads without you. He stops at every one. He’s far too young to cross on his own even if he thinks he’s looking both ways for cars.

Try to stay calm and talk to him quietly. If you get hyper he will too.

Can you do a quick to digest snack, good drink of water and let him play in the playground for a while. That would help him to calm down - I can't talk to my 4 year old for 5/10 mins till shes had her snack and the sugar seems to get into her system.
Talk to him at the weekend when he's not tired and agree some ground rules together that he's prepared to stick to with a high value reward.
E.g. really wants xxx toy - can have a jar building up to it. Each day he gets 10 mins in playground to be silly, then walks home in sight of you and earns a marble for his jar. Mine responds better to positive consequences than negative ones. But we need to pick our moment to talk about it - usually after lazy breakfast at the weekend not when rushing to and from school.

I think I have an action plan now. I will relax a bit about him running ahead, but absolutely no going around corners without me and he needs to wait at all roads for me to cross with him. I don't care if the other children don't do that, I will explain that those are my rules or he needs reigns.

I'll do the list thing for leaving the school grounds and meet him with a snack which will hopefully distract him

Good plan! Best of luck!