Hi op, I feel for you, 5 out of 7 nights until that time is a lot but you’ll kill yourself waiting up until that time so often.
I have a son the same age and after having their A levels cancelled and in lockdown for so long, they need to see their friends now and let off a bit of steam.
I don’t wait up for my son, he is my second eldest and I got used to not waiting up for my eldest (now 20) . I did wait up for my eldest initially when he first started going out but when it got much past midnight
I couldn’t do it as I had younger ones to get up and look after.
When he’s at uni, this is a ‘normal’ time to come home so he’s just started a bit early. I would try not to fall out with him so close to him leaving home. When he comes back at Xmas etc he will also probably be out late again and won’t want to be told off after having been at uni with complete freedom.
If you trust him and he doesn’t drink too much then try and relax a bit. If you are waiting up until 4am and say something happened (your worst fear) and he didn’t come home, is this much different to finding out at 7am if you went to bed early and got up at 7am. It’s only 3 hours later and saves you sitting up all night, also what if he came home at 5am or stayed at a friends. At what time would you know something was definitely wrong and needed to call the police?
As they get older you have to move from managing all their time and movements to gradually letting go, it’s hard to let go when you’ve had responsibility for their care for so long but as a single parent you really can’t sit up every night.
Ps be prepared for some further adjustments when they come back from uni but don’t be afraid to make some ground rules either. I always explain when they are home, they are not at uni and need to follow some house rules even if they are independent. Good luck.