The trouble is - without outside intervention I can see it becoming a huge thing that involves even more communication trying to get him to agree to a set place and time, and he won't want to do it.
Your issue here is that you’re envisaging ‘more communication trying to get him to agree’ - but he doesn’t have to agree. You actually don’t need his buy-in to set a time & place.
You can inform him that
Twat, as discussed it’s causing the DC - 13 in particular- a lot of anxiety not knowing the plans for contact are fixed.
The court order states you should let me know 5 days in advance. If I haven’t heard by then, I’ll be with the DC outside McDonalds at 11am every contact day. I’ll wait til 11.30am to handover.
I’m happy to vary this agreement to wherever suits you on your contact day but I’d like to establish a regular routine for the DC that is predictable - a fixed handover location and time if I have not heard otherwise by 5 days in advance.
He doesn’t have to like it. He doesn’t have to agree it’s a good idea. He can dispute the time and the location and whatever.
But once you’ve stated it - in writing so you can then point to the court that you’ve made him aware the lack of planning is detrimental to your DC - then you can grey rock:
Thank you, Twat. I understand your points, but I feel it is in the DC’s interest to have a fixed meeting point and time agreed between us. As I stated, I am happy to vary time or location if you let me know more than 5 days in advance. After that, I’ll assume contact is happening at the fixed meeting point.
And repeat. And repeat.
Pick a meeting place that the DC will like, so McDonalds or wherever you can treat them in some way if he doesn’t show up.
Get a special Twat email address you only check once a day. Get a rubbish mobile too if you like with only his number - only check it on your schedule.
Yes, you need to be contactable because he’s the father of your DC. But “being contactable”doesn’t mean he needs an Insta to response hotline to you.
Unless he’s got the DC in his presence, there’s nothing he needs to say that is urgent enough that it can’t wait 24-48 hours. Nothing.
So you set the terms, for yourself.
He doesn’t need to agree. He doesn’t need to like it. You don’t need to communicate over his lack of agreement or care about his opinion.
You just need to a) set out your proposal b) manage communication (grey rock responses, limited access to you via email/phone) and c) stick to your boundary.