Taking PCCN in 2 Weeks - HELP!

Hello All!

I am scheduled to take the PCCN exam on August 14th. I am studying with the David Woodruff program from www.ed4nurses.com. I just took the challenge exam that is included as part of the program and only got a 64% on it. Now I'm worried that I should reschedule.

I am also studying with "AACN Essentials of Progressive Care Nursing" by Marianne Chulay and Suzanne M. Burns. In addition, I purchased a book of sample questions, but am no longer using it because I found too many mistakes in the material.

For those of you that have taken the test and maybe have used this system, do you have any advice for me? Is their challenge exam an accurate gage to predict how I will do on the exam?