Ronda, does any hair come out at 12 weeks? My pup has no shedding at all.
When do you start with the rake?
We don't really start doing those major de-sheds until they have lost that puppy "fuzz" and have some real adult coat in. My pup is about 12.5 weeks and you can see the strip of adult hair coming in on her back...its thick, coarser, and much shinier. Occasionally I get a little bit of her puppy fuzz on my shirts but not enough to really have to rake. You can totally get her used to the rake though by lightly using it all over her although I doubt you will get any hair out at this point.
One more thing, as a groomer, start getting them used to grooming now, when they are small and easy to bribe!
Clipping the tips of nails, handling feet, cleaning ears and getting used to a soft puppy slicker brush now will pay off loads in the future, either for you if you do your own grooming or for your groomer and your pocketbook if you have it done professionally. I start a lot of pups at 10 weeks and by the time they are unruly adolescents, they are stars for grooming at least. I have a brother and sister set of gsds that I have been grooming since they were 9 weeks or so and you could not ask for better behaved dogs...they lift their paws up for nail clipping, jump in the tub, love to be dried, and are joys to do. On the other hand I have a female gsd I do that is extremely timid and resorts to fear biting when she gets really overwhelmed...she did not have her first grooming experience until she was 18 months...over the last year or so, she has made great progress and I no longer muzzle her for grooming but it took a lot of time and patience, cost the owner a pretty penny for the extra time, and if anyone other than me has to handle her she gets muzzled for safety.