I think working on the education piece and building motivation before starting ERP is so key. Kids need to know why responding to OCD grows it and is harmful long term vs just doing exposures. They also need to be motivated and cheered on. Bravery points and incentives help with this. It is also important for the steps to be small enough that they don’t overwhelm the child, but put them to the edge of discomfort. The idea is to build their skills for a life time.
ERP can cause anxiety – the very nature of exposures is to sit with discomfort which is often anxiety. But it is a balancing act of finding the edge of that discomfort without going over the cliff.
As kids get older we won’t notice OCD as much. Our kids often move towards mental compulsions (and if they aren’t educated on this, they don’t even know they are feeding OCD) and other compulsions that are not as obvious.
I personally would still want to teach a child skills if they show any OCD tendencies. OCD is like termites, even a little termite problem makes me nervous.
You could just work on the education piece and eventually move into the “defense” piece (e.g. what he does when OCD comes knocking). I would go at his pace and start where he is comfortable.