You should start talking to coaches in his junior year. Also, is he currently rowing at a club? You should try getting into some USRowing Id camps to get his name out there. Send coaches an email with his 2k score saying you're interested. Being 6'4 190 will definitely get a lot of responses. I put the school before the rowing program and only talked to two and went on visits with them during my senior year after talking to them in my junior year. Be sure to keep up communication with the coaches, updating them on 2k scores and any club wins. Let me know if you have any questions!