Agility -- how fun! IMO, training should start young.... just remember the attention span of your puppy and do not push too hard. You want to ensure the training is fun and short sessions for your pup. And always stop on a positive note even if it means going back to a very basic command. In addition to basic training, I suggest focusing on target training. Here in one method using a clicker
Target Training | Karen Pryor Clickertraining.
Even though they adjust the levels for our little babies I would recommend getting your vet's buy in based on your baby's individual needs (i.e., bone structure / muscle development) before starting any jumps, etc.
HAVE FUN!!!