I have 4 collies LST and a few other fosters in the mix plus other dogs.
Your pup is too young to do the full agility training but he is more than ready for the preliminary training.
Totally agree that he needs to be taught calm and the clicker is the way to go with collies.
Collies are full on BUT they do learn to chill really well. People think they are on the go all day but my labs/spaniels are much harder to teach to chill.
Teach him to target with his noise. Get a plastic pringle lid when he touches it with his nose click and treat- this can be done with you sitting on the sofa. This will help him to understand his agility contacts. Teach him to stand on a step with two back feet on the step and front feet on the ground.
Teach him to spin to the left and to spin to the right - this will help with directional commands when doing agility.
Get him used to running with you - run in a large circle with him outside of you -
Then run in a circle with him on the inside much harder!
Teach him to wait so throw toys etc play with a tuggy by yourself and he has to wait until you give him a release command before he can get it.
Do not ignore him when he is calm. - click and treat the down position as many times in the day as you can.
If he has had interaction with you during the day, exercise, training etc then he does need to be taught calm. It may be a six months that he does need lots of little bursts of training but once he has had that he must learn to relax.
Collies are fab dogs, so bright, so empathetic, so up for most things - the more you give to your lad when he is young the more you will get back over the next 16 years - they are a joy to be with.