I have quite a bit of gray hair in the front section of my head. It's been a while since I got it covered, and the stylist didn't look familiar so I think she is new. When she started my hair, she started from the back of the head (bottom) and worked towards where I have the gray problem. I'm not a stylist or anything but in all honesty I would assume you would start at the gray coverage area to let it set in longer.
When it was all said and done, I glanced in the mirror but didn't really check thoroughly (I wasn't feeling the best so was in a rush to leave).
Well, she didn't cover the gray hair very well, there's still brown color (natural) that I asked be covered, and she didn't color all the way to the roots of the gray.
Not happy with the hair service however my stylist is out on maternity.