Thai Pass have a 72 hour cushion but I don’t know the specifics but potentially you could leave a couple days earlier but I would check the conditions.
Sounds like you need a babysitter for your son while you go to Thailand
Jokes aside that’s super shitty, I ended up taking a pretest 5 days before my travel test and laid low until my trip. From what I’ve seen the typical period for testing negative for Covid after infection is somewhere 10-90 days with the average being 3-4 weeks. See what the meeting Jan 4 brings, good luck.