My yorkie Fido is 1 year and 1 month old, but has still loads of black on his back, stumach and litle bit on his feets.
He will propably be all grey around 3 years.
He has grey on most of his face, on his stomach and under his tail, and the half on his feets
I always see more and more gray hairs
Its not bothering me much that he's not all gray.