[gracielove]

Any dog will do better by staying with the mom and litter mates until 12 weeks as they learn a lot during those extra weeks about social skills and become more able to adapt emotionally to the outside world. Yes, dogs do have to have social skills and they need to be able to emotionally adjust to various situations in life. Beyond that the Yorkie in particular, being a smaller dog, can have problems adjusting to eating only food and no mom's milk. They have a tendency to become hypoglycemic and that can be fatal in a young pup. It is possible for an 8 week old pup to survive of course but it is so much better for mom and puppy to have the time they need to adjust properly as they would in nature.
As I suppose you will pick the pup up anyway I do hope you bring some nutra-cal and some Esbilac just in case. Esbilac is a powdered baby milk for supplementing puppies. Never give a young puppy cow's milk. There are other brands of supplemental puppy milk but Esbilac is the more commonly known brand. Yorkies can be very picky eaters and a young puppy should not go without eating for long periods of time as their blood sugar level can get low quickly.
Hope all goes well for you. Get as much info from the breeder as possible and make sure you can reach them by phone around the clock.