"No-shampoo" hair: baking soda frequency?

Alright, so I'm thickly wavy-haired and whatever shampoo and conditioner I use, whether I blow-dry or avoid it like the plague, can't keep my hair looking unfrizzy or curlier like it used to when I was little, so I decided to go shampoo-free. My hair, for all its frizziness, can take a beating, but exactly how often should I use baking soda and apple cider vinegar?