Weekend after. People still have plans a couple days before Halloween because I have a Halloween event on the 26th, because it falls on a Saturday. So most places doing events will be doing it the weekend of the 26/27 just because it’s the weekend. So I say do the birthday after. Definitely. If you do it the week before don’t be surprised if people reply back “we’re busy! We have a Halloween event. We’re invited to this other thing” etc etc.
If you want to do a costume party, you should do it the weekend before. If you want a regular party, do it the weekend after.
Weekend after because a lot of people have Halloween parties and pumpkin picking the week before!
Weekend after, otherwise it's still all about Halloween. Take down the Halloween decorations and celebrate the birthday boy! 🎉
After. Especially as his birthday is on Thursday so towards the end of the week.
I think there will be less going on the weekend after and will give you time to send invites and hope no one has made prior plans.