8 weeks is pretty standard for the minimum. Unless there are issues like the mother trying to kill the puppies. 8 weeks is also the legal minimum age for a lot of areas too.
That's a shame. Honestly the longer they're left with mom, the better. Of course it does depend on the bitch too. With my BC, I got him at 7 weeks of age. His mom was notorious for being done nursing puppies almost as soon as they start eating solid foods, around 4-5 weeks. But he wasn't separated from her or his siblings until I bought him at 7 weeks old.In the rescue to which I belong, it is common practice to remove the momma's from the pups at approx. 6 weeks though it has been done sooner. This while these momma's are still heavy with milk. I've taken issue with this and been told that
"Clearly you know nothing about puppies or animal behavior" by the woman behind these decisions.