Sinister started getting his shiny slick adult coat around 13 weeks. It started as a small stripe down his back and tail. Now he is 16 weeks and has very little puppy fluff.
My other German Athena was a long coat so she got her adult coat a little later than him.
Athena- Long Coat GSD -CGC
Sinister Black- GSD- AKC S.T.A.R. puppy