I was told that jumping should be after the age of 1 year when the dog is full grown. However some jumping prior to that is fine but the jumping should be limited to nothing higher than the puppy's elbow. Rooney (10 months) has been jumping in agility class - outdoors, keeping the the rule above.
Hey Stacy....I agree with everyone's comments. You want to wait until the growth plates are closed. Parris is 15.75 inches at the withers and we started jumping 16 inches when she got into the intermediate level at agility....around 18-20 months old. In "puppy" class the jumps were on the floor a lot of times.