I'd be wary of any book that advises something different to the current guidelines. Lots and lots of research goes into the guidelines. Definitely dairy is ok at 9 months, but I wouldn't be giving cows' milk until after 12 months. It is unlikely that your lo will have a problem with cows' milk when he's older if he's tolerating the formula ok, so I'd just hold off on the milk until after he's 1. Is there any reason other than the book that you want him to have milk already?