Many, many years ago, I sold puppies to families. I always met them ahead of time, before the pups were born were born, and had a little 'class' in which we went over the beginnings of what to do, and not do, with the puppy.`
I remember one family came again, after the pups were born, but not old enough to leave Mom. They had a little boy (just him, no siblings) who did not come the first time (it was for them to approve me, and me to approve them). He was about 6, very smart and well behaved, and went out to the dog room. That was the year I had some oops litters, all born within a week of each other, and he was so excited to just get buried with puppies! I think they were about 6 wks old. I took photos of the whole experience that day, and made a special PRIVATE page of "Ethan's day with the Puppies"
We went over my 'getting a basenji puppy' class and he was so attentive. I never got a call from them about any problems - I'm not surprised, he wanted that puppy so much.