If you're now feeding a Large Breed Puppy food (i.e., for dogs that will have adult weight over 50 lbs.) the canine nutritional science studies that described the preferred formulations of a LBP food recommend feeding that formula for the first 12-18 months of life to reduce later joint problems as much as possible. Feeding a LBP formula is of most importance at the earliest ages and very gradually becomes of lesser importance the older the puppy gets.
However, as you see, in the 'hood there's all sorts of different opinions and practices.