Changing jobs in the Navy?

I'm an NROTC cadet at Texas A&M and I plan on commissioning as a Surface Warfare Officer. However my main objective is to become an Intelligence officer. What's the process for switching job clifications, how long does it take, and how long would I have to be a SWO before trying to switch over? By the way, I'm a double major in Political Science and Sociology with a minor in Psychology if that helps. Please don't answer if you aren't in the military. I'm looking for legitimate answers, not guesses from civilians.