I would start your pup on adult food right away. Puppy forumla, even large breed puppy food, is meant to help them grow. But with a saint, because of hip dysplacia, you really want them to grow as slowly as possible to help minimize the effects of HD in the future. The sooner you start your pup on a high quality adult food, the better off they will be for life.
I recommend looking at the list of "whold dog journal" approved foods and seeing which ones you can get in your area. I would suggest you go to your local pet stores and get a list of the foods that they offer. Then you can compare the foods online (with the help of the wdj list and of course your friends here at bpo).
Whatever you decide to get, I would start with a small bag of whatever your breeder is feeding so that you can slowly transition the pup
