Just some advice for a first time puppy owner.
First off, Yorkies are amazing!!! I have had many breeds and I am a Yorkie owner for life.
Second off, please make sure you can take care of, train, and accommodate a Yorkie. They are special little dogs.
Third, definitely read threads here and ask questions. This is a great side.
Buying a Yorkie research on the breeder is very important. A well bred Yorkie can live long happy lives, whereas a mis bred Yorkie can suffer from issues such a Collapsing Trachea, Luxating Patella, Liver Shunts, and some other issues. Most Yorkies to a certain extent do have LP, so its also good to know how to care for Yorkies in general.
Yorkies are Big Dogs trapped in little Dog bodies. Make sure you Yorkie proof your house. I have heard of too many Yorkies falling off balconies, drowning in buckets/bath rubs, and falling down stairs. You have to make sure that your house is ready for them. Also Yorkies are totally like little humans so make sure you lock up anything you don't want them getting into, because they will get into everything
Yorkies are very protective of there owners and a extremely stubborn so make sure you have good patience with them. They are extremely loving and only want to please you but you also have to be the Alpha in the pack and not let the new little one run your house too much. A lot of first time puppy owners who own Yorkies end up letting the Yorkie have to much control which can develop bad habits like nipping, barking, and over protectiveness.
Yorkies are amazing. Keep doing research here, find a good breeder, and get ready for the best years of your life with your new furbaby!