Knock sensors are constantly working to either add or subtract timing based on knock activity and other factors. There are a ton of other variables in there but it is somewhat instant.
Thanks for the replies. With gas going up almost daily and premium being .60 more than regular, I put some 87 in the other day and was waiting for a change in performance. With my driving style I didn’t notice much of a change except my wallet was a little fatter when I left the pump. I think the ole Mustang will be sipping 87 for awhile.