I started my IG puppy in agility at about nine months old. She will be in the 16 inch jump height, but for training, I've kept all the jumps at 8 and 12 inches. AKC doesn't allow dogs to compete until they are 12 months old and USDAA is 18 mos old. There's lot's of things you can do to get a puppy ready for agility from jumping poles on the ground to getting use to having something move under foot, like a wobble board.
I was very iffy about starting Lizzy (YT) in agility. She was not socialized at all before I got her and had no training at nine months. She does not like other people or other dogs. She is very snippy with other dogs and fearful. I really didn't know if she could work through her issues. Happily she could and she has become a great little agility dog. She is very fast, willing to learn and confident in agility. She is a momma's girl and I was worried she wouldn't work away from me, but again, she has surprised me and will go out for an obstacle. Her arrival in my home took the place of the agility puppy I had been dreaming of, but she was the youngest and only dog I had to train in the house. Her number, so to speak, came up. I really enjoy training her and running her.
I would absolutely give agility a try. It is so positive and so much fun. It's a great way to strengthen your bond with your dog. For great information about agility go to
www.cleanrun.com