My general rule for Toy breeds is that they should never be separated from their mothers until 10-12 weeks. Toy breeds tend to take longer to develop normal behavior. It's also vital to keep them with their mother longer because Toy breeds are more susceptible than large breed dogs.

So, may I ask where you're acquiring this puppy? Are you getting her from a breeder? If so, I would run away from this breeder. IF you are having any doubts about the age in which she is selling the puppies, ask her why she is selling them at such a young age and if you don't receive an acceptable answer, run away! 6 weeks is much too young for a Toy breed, imo.