When do you starting brushing/cleaning gums?

You can inculcate the habit in your newborn from young. It's good to get them used to the idea of brushing their (future) teeth. I started cleaning my newborn's gums from the day she arrived home. Wrap a wet washcloth or gauze and rub it gently across her gums. http://www.babycenter.com/0_how-to-care-for-your-babys-gums-and-emerging-teeth_126.bc