When our puppies are 7 weeks old, we can do a puppy test by a graduated behavioral expert. That way, we can already judge the character (which we also have seen in the weeks before) and the work drive, after which we in consultation with the behavioral expert, assign the pups to the different aspirant puppy buyers.
We bottle feed our puppies fresh meat and also do this to the mature, doses and vaccination measured to size, so we measure if there are any antibodies in the blood (titrating) and only if they are at a low level, the puppies get their vaccination. This is because we do not need the puppies to be stuffed at an early age with vaccines that cannot catch on because there are still antibodies in the blood (measuring is knowing). Custom vaccination is not cheaper but better for the dog. We are not against vaccinations but against unnecessary vaccinations.
In addition, we work with a list of interested people where people are added to after a personal meeting. Once the puppies are born we let them know if there is a puppy for them. Both parties hold until the day that the puppy may be retrieved, the right to refrain from taking/selling the puppy.