I am curious how others manage the issue of giving notice. I personally tend to seldom know for sure where I will stop for the day until I am there or very nearly so. I seldom even know if I will be staying in a given town much less when. As a result I manage to stay with warmshowers hosts pretty seldom. I usually ask if they are OK with short notice when I make contact before the trip and skip any who are not. I then carry the culled list and usually manage to miss most of the potential hosts.
That said, when I do (rarely) manage to be a guest or host it has always been a positive experience.