Take a deep breath....you have very little time to learn all the essentials of each style - but you can still cram to get a basic premise...If I were in your position, I would do the following:
Read all BJCP styles 1-19 and 22 over and over and over every single day if you can.
Read the troubleshooting section of the BJCP study guide over and over and over every single day.
There is also a good section in the BJCP study guide that tells you how to evaluate - read that, especially if you are new to judging.
Keep in mind, that your objective is to become a better brewer - you can always take the tasting exam again if you choke, and if you have already completed the written/multiple choice part, then you have a great foundation. Have fun learning about all the beer styles and tasting at the exam!
For my exam, I modified the BJCP styles into a table format to make it easier to study - send me an email or PM with your email and I'll send it to you as a word attachment.