How long does it take for a border collie's color to come in?

A dog's full coat can sometimes take a full year to a year and a half to come in. I know this as I have two Siberian Huskies and their coats seemed to take forever. They are both over two years old now and their coats are still changing. Not quite as dramatically as when they were younger though, and my dogs mane is still developing. So don't stress too much, it takes as long as it takes.