fias Co farms has some pretty good info. Without seeing the doe there really is no way of telling. I can feel kids from about the end of the 3rd month to kidding.
It takes roughly 145-155 days from mating to kidding. The udder will enlarge as she gets closer to kidding. I have one due in June that is building her udder. Its a process and doesn't usually happen overnite. I figure that mine start building at 3 months of gestation and continue to grow...