I would get a sweater or a jacket. Both of our yorkies wear XX-small or X-small depending on how the outfit looks. Some of them are made small while others are made big!
If you want your puppy to wear clothes often then I definitely suggest starting young! Our oldest just knows when we buy her clothes... She loves it! She'll drag the outfit out of the bag if we don't pull it out for her in time! She never chews on them either... She takes such good care of all her outfits!
__________________ Proud mama to two little yorkies! 
Gigi - 11 months and Stacy - 4 months! |