Sounds like there could be underlying issues at play here. He seems overly aggressive for one so young. I would start with a GP appointment and hopefully they can give a suitable referral

He sounds very frustrated.
I agree that you should try to find out why he is behaving in the way he does and be pro-active not reactive.
I think for a 4yr old it can be still very hard to recognize emotions. First of all I think it’s very important to spend enough 1-1 time with him and chat about everything what’s happening in his life. Some children need more time to adjust and it’s important to prepare them well before a change is happening. Help him expressing it and labeling it.
When becoming physical is his outlet I would create a moment / safe place where he can be physical. Karate for example could be very good to do this in a controlled way.

Behaviour serves a function and what you need to do is work out what he is getting by behaving in this way. There are any reasons for behaviour such as seeking attention or having difficulty in getting his needs met (can he express himself sufficiently). If you can come to some sort of a reason as to the ‘why’ for his behaviour then you can make sure that you are not reinforcing it without knowing or realising it. Have consistent rules and consistent consequences for the behaviour that you are trying to change. Make sure that you focus on the behaviour not being okay, and not the child. Reinforce when he is making appropriate choices. The hardest thing is remaining consistent and that Mum and Dad are both on the same page giving the same message. You won’t get changes overnight and behaviours can often increase before they start to reduce, so expect that this may take some time to change.

set boundaries and rules to follow. if there are any developmental concerns consider if there is an underlying disability causing the behaviour. He’s still only young and should get the routine soon enough – if not maybe wait a bit longer before he should start.

Unless he is going to be 5 pretty soon i’m surprised the school took him. Starting school is a big step. They are suddenly there 5 days a week, like many his age his concentration span could be short and him get bored easily. If he has only just started school his homework should only be reading which a parent/ guardian/ other responsible person is required to help with. Perhaps addition etc. if the school is being “pushy”. He is probably tired by the end of the day. Maybe let him have a short time to relax and “unwind” before starting homework. Have you been told exactly what he does behaviour wise at school besides yelling and hitting. It may be that he is legitimately defending himself. I remember my 2 nieces were taught within a few days of starting school that if they didn’t want to do what their parents ask them to do they don’t have to…..and a few other things. Another of teachers’ phrases during that lesson was “Kids have rights”. Kids are smart. It doesn’t take them long to work out that teachers are adults the same as parents are….so basically they are behaving how they think they can because they have rights. I would ask the teacher if it has been mentioned in his/her class. Does your son only want to read books with pictures in them? I know a boy who was doing that. Tests proved he was dyslexic. They also discovered he had started to write some letters of the alphabet incorrectly. I know he had special glasses but I don’t remember the details. I think it was something like the colour of the lens

Four years old is very young for Prep. In Victoria, you have to be five before you can start Prep. Maybe he is acting out because he is overwhelmed and tired. My gut feeling would be that a few days at kinder each week might suit him better.

I would make a list of expectations and things to do when your expectations might not being met. Be consistent with whatever you decide. It could be a behavioural issue that needs professional help, but see how you go yourself first

Talk to his teachers about strategies but I would recommend choosing a strategy and be consistent. If it doesn’t work bring in an expert.