I passed the June 2012 level III exam on my first attempt.
For back ground information, I failed the 2008 level I exam (band 10), passed the 2009 level I, failed the 2010 level II exam (band 9) and passed the 2011 level II exam - my wife gave birth to our first child a few days after I sat the 2011 exam.
I started studying for the 2012 exam in September 2011 (with a baby screaming in the background) and took all of May 2012 (5 weeks) off of work to complete a final review the material. The real key to PASSING the level III exam is to do as many practice exams as you can. If you can consistently pass the practice exams (overall score of >70%), you’re in a good position. Learn how to answer the questions the way the CFAI wants you to answer.
Make sure you have a schedule and stick to it. It is important to try to do something for yourself at least once a week.
I wont lie, it is hard work, but it gets results.
Good luck with your study.