I switched Smudge over to adult food whe he was just over a year old and Winter got placed on adult food as soon as I got her which was at 11 mnths, they eat different foods now because Winter can't handle high protein it trashes her coat and Smudge needs a reduced fat food because well he's a pig. But I think most vets or trainers suggest around a year is a good time to change the food...at least that's what the ones I've talked to say. What you might want to do is phone your vet up and ask them what they think or get they're advise as to when you should change...because people in the pet stores don't always know everything aboout the situation and can't give a proper opinion without it.