I am sorry to barge into the conversation like this but seeing buyers early is very common on the continent. As I am originally from Germany I have always kept it this way. Our puppy buyers come from the first week on but are not allowed to touch the puppies or sit directly by the whelping box. My puppies are in our office for the first two weeks as I spend a lot of time in there but there is no coming and going. So any potential puppy buyer (who are only allowed to visit at weekends) will be able to take a quick glimpse at the puppies but then we move on into the kitchen for a talk. After their first two weeks the puppies move into the kitchen where everything happens in this house (it is rather large with a big dining table etc). From the time the puppies have their eyes open puppy buyers are allowed to touch them too. With four and a half weeks the puppies move to a Summerhouse within a large enclosed area outdoors where they have plenty of toys such as tunnels, sand boxes, tree trunks, paddling pool and whatever else's I feel is important to socialise puppies.
Having said all of this - I think many things need to come together when you go about choosing a breeder. A statement such as the promise that a white patch on the nose will disappear would make me more mistrusting as it almost sounds that the breeder is trying to persuade you to buy the puppy........... The other worry would be the fact that the breeder is offering you a choice at this age. Not only is puppy survival not guaranteed at this age but there is also no way of knowing which temperament the puppy will display and there can be huge variations. One more concern in this department would be the fact that most reputable and well established breeders would have at least some show enquiries for the litter which means any pet home would have to wait until the breeder has made a decision regarding the "pick of the litter". When my litters are born it is more than likely that the puppies are already spoken for and it is very rare that I have not met potential buyers before the birth of the puppies. Would they be complete and utter strangers that did not sound to promising over the phone they would not set foot into my house while a litter was about.
Greetings,
Stephanie