What I see above that is different is structure. His parents and school provided some structured activities and opportunities, and now he has to provide that on his own. This requires executive functions such as planning, ordering, and executing actions. I suspect this is the biggest problem for your son.
Life coach is one way to look at it, but occupational therapists can also work with an adult to learn some ways of dealing with this. But it will need a client (you, or your son) to express what is needed and oversee it.
Can you talk with your son about this and other ideas you have been offered here? Then you could get buy-in from him, hopefully, without which no change is likely to happen.