Hi and welcome to YT! It sounds like you are well prepared for your new baby. This site is a great source for information, you will love it. Yorkie puppies are very active and do get quite a bit of exercise on their own. That is sure the case for my little girl Roxie. She is 4 1/2 months old and gets plenty of exercise from chasing her ball, rope, toys, etc. She also LOVES to go on walks and playing outside. I live in south Florida so I try to keep outside activity to the early evening when it is not so hot and humid. She lets me know when she is tired and I am sure your puppy will do the same. Congrats and good luck with your new little one
