M.B.
I wouldn't do it before baby is crawling after reading about John Travolta's son and the carpet cleaning chemicals. I guess some of the mental problems he had were traced back to the Travolta's cleaning the carpets too frequently when their son was little and crawling. Just think, those chemicals are laid on and then dry on and then your little one will have his face right there and his hands there too - even after they dry, the chemicals will still be there. Any germs from previous families will be gone after a month, so I would just vacuum the carpets well. Anyways those germs are probably a lot safer for your baby then the chemicals they use in carpet cleaners - whether your hire professionals or rent a machine.