My Lucky was almost 3 years old when we adopted him. No puppy stage to go thru, no housetraining and he is the sweetest dog you could ever ask for.
If you plan on getting that dear 1 year old Yorkie, since his testicles have not dropped and if you want to get him neutered, it would be a more invasive procedure than if they were allready down. Best of Luck to you.
That is so... great your considering adopting an older dog.