each goat is different. I had mine start at day 75 I believe it was - but they are only pygmies and nigerians I would assume with a nubian starting early would help them fill it up .
I was kind of worried from what I have read 4 weeks before they kid is normal. Jesse is a FF but she is from good milk lines.
Mine start bagging up about a month before they kid, some earlier, some do it right before they kid. Every goat is different