If there isn't any chocolate in the lines, most of pigment usually is in by the time their eyes open. That's just a rule of thumb. It can continue to darken and fill in for a long time. Several years ago I got first pick of the litter of a male from friends who gave the boy up because of spotty pigment. By 6 months old his pigment looked like I had used heavy eye liner around the eyes and lips and nose looked painted. His puppies do the same thing - initially spotty pigment, but around 10 weeks old, it really fills in.

Sire Chocolate dam black she started getting her pigment day 3 or 4. First on her pads then her nose. She has good pigment now. Thanks everyone!

Yes, but since you had both yellows and chocolates in the same litter the black dam has to carry chocolate too, so it was possible for the yellow to inherit the gene for liver pigment from both parents, you got lucky she inherited black pigment.