Sleep Routine advice, son doesn't sleep at decent time.

Hi everyone.

My child is going to turn 5 and has started p.1 (Reception), I'm struggling with a sleep pattern for him he hates going to bed early and can't get up in the morning. I have two younger children and it's hard to get into a routine. I don't know how to get him to listen.

Can anyone advise:
1. What time should a 5yr be going to bed to get up by 8am?
2. Any tips or advice on how to sort out his sleep habit?
He wants me to sit with him till he falls asleep and that's not practical with two other kids.

Thanks
Zak