When we were looking for Ellie we went to look at some 5 week old puppies. The breeder was surprised that we wanted to see them before they were ready to go. She said that people usually just rang up and then sent a depositin the post. When the puppies were ready to go then the people came to see them and the order which people could choose was the order that the deposits had been received.
She was obviously quite happy to let her puppies go to people she had never seen. We walked away.