It is beneficial for the pup to remain with it's mother til at least 12 weeks. They learn so much from their moms from 7 to 12 weeks. Not to mention that the pups should have at least 2 sets of shots before they go to their new homes. A dog will bond with you at any age, as long as you love and nurture it. The period from 12 weeks to 16 weeks is when they should be learning what you as it's owner expect from it. Pups go through their first fear period around 7 to 8 weeks and this is the one that sticks with them.
Developmental Stages
Granted alot of sites like this say 7 weeks is the best time to bring a new pup home with toy dogs it's not because they are just getting started eating real food and all they learn regarding socialization and potty training and such is what the breeder should be teaching the pups. That way when you bring your pup home you continue it's training.