Six weeks old is about the right time to introduce your puppy to a bath. But I would wait until she is more settled in the house beforehand so as not to frighten her. You can brush her or use doggy wipes (not baby wipes) until then. When you do bathe her, make it a pleasant experience. Offer treats at each step and speak softly. Show her the spray before applying it to her body and use a gentle spray. Massage the soap in gently to give her a good feeling. Rinse all the soap out well. Dry your pup gently with a soft towel. Keep the pup warm and take her out only when you are sure she is thoroughly dry.