How old should my german shepherd puppy be before I feed him large breed puppy food?

My german shepherd puppy is 10 weeks old and I have been feeding him regular puppy food. My breeder said I should wait a certain amount of time before I feed him large breed puppy food because of something that has to do with how fast it makes them grow & it's now good for them???
Has anyone heard of this or do you know if I should start feeding him large breed puppy food yet? Thank You