[mscat]

Hi there and welcome to YT . you are right that 12 weeks is the ideal time to bring a yorkie puppy home, and even at this age they need so much attention. A responsible breeder woud never sell a 8 week old pup >
Mine was going on 9 weeks old , and I was at home all day long with her. I did not know any better either. Hypoglecimia is the thing that is the mot scariest part about bringing home such a young yorkie baby home . They have to eat often , and sometimes they do not want to if stressed out , and in a new environment .
BE sure to have Karyo syurp on hand to give if she is not eating rub it on her gums to prevent any hypo attacks.
If at all possible , have the breeder hold onto her for a month . That is anther important thing is that these pups learn social skills from each other , and this is the critical age for doing so.
If I were you I woud have an ex pen ready , puppy pads , toys, and have someone check on her every few hours , make certain she is eating .... A tiny pup can die of a hypo attack , so it is really vital to make sure she is eating well.