My pup is about 4 months and I just try to get her used to dogs on our walks. She's a bit chicken, but I always ask the owners from a distance if their dog is friendly with other dogs. If so, I make Raika get close just so she'll get used to it. Usually within a couple minutes she's fine. Just keep trying. I don't think he's too old to do that. 4 months is pretty young still.