The guideline is a year of age. However. some agility training facilities offer fundamentals classes where you do a lot of the agility stations but there is no jumping. Or the jumps are like 4 - 6 inches so your dog learns to pick up their feet. You could go through this a few times and work on obedience as well. Also, rally offers exercises that are super helpful in agility as well. And, rally novice has no jumps and many people can put an RN title on their dogs while they are still relatively young.