I think that you got alot of great info already from topknot
I just wanted to add that it helps alot to keep your puppy's coat really clean and conditioned when your trying to grow them out. when their hair is too dry or dirty it can cause the hair to get mats and or break. Brushing a dry coat will cause breakage too and can make it seem like your not getting much growth. I spray a little conditioner in first and then use a pin brush on my babies, and a metal comb on their faces. You might already know this but I thought I would add it just in case
I know some people who's coat didn't reach the ground till the dog was almost two.
I would love to see pics of your baby!