@Kathy45 Yes, both hosts and guests are sent messages asking each to leave a review.  Lately I've been getting a review prompt less than 24 hours after my check out time.  Usually I wait until I clean the entire place before I leave a review. 
I have a guest that checked out over a week ago and hasn't left a review yet.  If she doesn't leave one by Wednesday, I'll send her a reminder.  Sometimes when people are travelling and don't have ready access to the internet it takes a while for them to leave a review. 
How long ago did your guest check out?