Welcome to YT and congratulations on your new Yorkie baby!
I am not a breeder and don't understand the "rule of thumb", however, we had to
pry Toto from our breeder's fingers at 16 weeks!!

I understand the importance of waiting now, but at the time thought I would just die if we couldn't bring her home that day! She was only 1 1/2 lb. and after we got her home we were absolutely terrified! She was 2 yrs. in July and has proven to be extremely healthy and well-adjusted ... well ... maybe a tad spoiled!
Looking forward to hearing all about your little ones and seeing pics!! Hope you find the forum helpful!