As Emily says....
Coral started free hunting at about the same age. It's back to basics I'm afraid - confined area for training, that he cannot escape from and lead walking only.
We are now attending regular 1-2-1s with a gun dog trainer, I'd suggest doing the same, it's worth every penny spent now and they will assess Austins requirements which may differ from other cockers (Coral is very different to Sally and both have been known to free hunt).
Don't worry about "exercise" he is still a baby and can manage just fine without lots of physical jerks - brain training and basic discipline /obedience is all you need to do at he moment.
Coral is on a 10 day plan at the moment, lead walks only, dummy training in a small area and lead /house line which is oermanently attached to OH
Austin is still very young - little and often for training as I'm sure you know - but he is about to become a teenager.......if he's allowed to free hunt now he will be very difficult to bring "back in" in 6 months time
. Also however good you think his recall and stop is now, don't take it for granted, a dogs hearing doesn't develop until 10-12 months old - came as a surprise to me last week when I was asked to turn my back then recall Coral - she didn't know what the 4 pips meant! She does now......
Good luck and enjoy Austin, he sounds like a wee cracker (great name too)