@Susan1188 If a guest cancels on the DAY OF ARRIVAL they will still be able to review . . . regardless of check-in time. For example, if a guest is confirmed to check-in on the date of March 4 and they cancel at 2 am on March 4th, they will still be able to leave a review. If they cancel on March 3rd they will not be able to leave a review.
They will receive the prompt to review as any other guest would (on the afternoon/evening of their check out day.) Hosts will also receive the same prompt.
Botton line: You should not be concerned about reviews unless the guest cancels on the same calendar date as their check-in.