When is the appropriate age to start Agility Training?

Timber is now 4 months old, he sits perfect, downs perfect, stays perfects, comes perfect (I am expecting this to change as hormones kick in) we are working on heeling, but I would like to get him started on the Agility side of things, I have been told to start on the Weave Poles, and I have been told to start on the Table and I have been told do not to anything until he is 100% obedience trained and does every command perfect everytime. He is very smart and learns things very very quickly, but I also don’t want to push him too much, and then it isn’t fun for him. Does anyone have any ideas on what to start him with on Agility or any books or links that would be helpful?