You take it near the end of the fall semester of first year. If you pass, that's it--you're done and you don't need to take it again. If you fail, you take a course in the spring (I think it's 8 weeks, but I'm not certain) and then retake the exam. I don't know what happens if you fail a second time. Also, if you're not confident about the first exam in the fall, there is a course you can take during the semester (again, I think it is 8 weeks) to help you prepare. This first course is voluntary, but if you fail, the 2nd course is mandatory.