I know breeders who bathe puppies in the 6-week range because no matter how much care is taken once they can walk, they play and explore around the whelping box and get themselves into feces. So I'd think you could bathe your puppy pretty much any time after weaned and home with you so long as you use very gentle shampoo and don't let him/her get chilled, but I wouldn't think most puppies need bathing so long as they're groomed regularly, which they need to learn to accept. Mine never did, although admittedly mine don't have the kind of coat yours must have.
Brushing and combing are more important than bathing. This is especially true in dogs who are a cross between breeds with vastly different coats (Poodle harsh and curly, Shih Tzu long, dense double coat), because you never really know what coat type (or combination of type) they will inherit. A pin brush and what's called a Greyhound comb over here are essentials. Teaching your pup early on to lie quietly for grooming will make you lives a lot easier. Check out YouTube for videos on line brushing, since that's the best way to groom a dog with a long, dense coat. Also, you can't bathe a dog unless it is completely brushed out and combed, because if there are any mats in the coat, bathing will just make them worse.