AmyMarie,
I would suggest holding off the cognitive therapy for the near term. It would be better to get settled with an understanding of his symptoms. The TBI Survival Guide at
www.tbiguide.com will give you some help at identifying the individual symptoms.
With a better understanding of his symptoms, plenty of people here can give you suggestions for ways to work with and overcome many symptoms.
Learning how to work-around symptoms will allow him to engage in more activities that can slowly stimulate his brain. Then, cognitive therapy can be considered as an addition.
My best to you.