Depends on the lines, pedigree, and individual dog. I've seen very nice pick pups turn out surprisingly bad and sometimes average pups not kept back turn out quite nice. But generally 7-8w will give a basic idea of how the pup is - ignore structure from 4m to one year - adolescents are very ugly and gangly as they grow. At about a year old, you can get a general idea of temperament, structure, and eventual development. Little later for slow maturing lines.