I was checking daily to see if the credit for this already posted and on 1/14 (2 weeks post charge) I reached out to Amex via chat just to make sure that the charge was eligible. The rep confirmed that it was and that the latest I would see a credit is 90 days later as per the terms and they are unable to do a manual credit prior to that. He also said that he sees the credit was already triggered and therefore I may see it earlier.

Very interestingly, today the $200 credit showed up on my account dated 1/14. I'm almost sure it was not there earlier because like I said I was checking this account daily for it. My meter for 2024 hasn't moved yet so I know this credit is for that 12/31/23 charge.