Dog portrait: step 1

I've been commissioned to paint another dog portrait and this time the breed is a Collie-Samoyed mix. As I have a short time frame to complete the portrait, I've decided to try something I've read some artists employ in their process, and that is to create a model (yes, I know it sucks ) for the purpose of determining the best lighting and for my reference.  I've begun the rough underpainting in greyscale.