Before we got our rice cooker (yay Mel you still totally rock!) Shel used to swear by constant stirring. For the whole time. And to check, bite a grain of rice in half, if it had a white dot in the middle its not ready. If its clear, get a spoonful of rice out and have a chew, see if its an ok consistency for you.
Long grain white rice generally takes 15-20 minutes from when boiling starts.