I can only write on my own recent experience, but am sure that others will chime in.
Nova came to me off the track in March. She's pretty much all black, except for about 6 white toes and a tiny white patch on her chest. She arrived a tawny brownish color, and as soon as the weather warmed up, she started shedding. I would brush out piles of fur every day. She pretty much lost all of the hair on her belly, the backs of her thighs, and her neck. I assumed that it was just how she was going to turn out, and was fine with it. But now, within the past couple of weeks, she is starting to grow silky black fur back in those areas.
The process has taken months, and I am just now starting to get a glimpse of what her coat will turn out to be like.