Though it's far after the fact, I want to share my experiences with the credit.

I booked two car rentals last year.

One was ~$125 on 5/28 and got the credit 5/31.

The other was a weird one. I booked it 9/23 for a 10/1 rental. My travel plans were cancelled due to Hurricane Ian, so I had to cancel the booking. I received a refund for the cancelled booking (Even though it was 'nonrefundable'). In addition, I received a travel credit for ~$175 on 11/1. Seems like a fluke and would not count on it, but I figured I would post the data point anyways.

Have to book another rental soon, so I'm hoping my credits reset shortly after the AF hits, like others have posted.

Happy Traveling!