As stated, you can earn a fail, provisional or pass rating. Fail means the instructor thinks you need more instructor time to pass. Provisional means you just need more practice. The instructor can set specific "homework" and can specify a time frame, but I believe standards allow you six months. (Some instructors will be flexible with this; others won't.) Once you have a rec pass, you can reevaluate for a tech upgrade at any time (this was recently confirmed on the GUE forums). You may or may not be charged for any of the reevaluations, at the instructor's discretion.