John,
As a rule of thumb we tell our students, that if you are consistently scoring 80% or more when you take a practice exam for the first time, then that is a good sign of readiness. However, take this with a grain of salt because we are all individuals and your personal readiness may differ. Some students work better on an exam when they know they are under pressure a bit, while other students are more risk averse.
Based on the 80% rule of thumb, and the results that you shared, it sounds like you are well on your way!
We suggest you study your practice exam results as well as your own mental assessment/inventory of your readiness to see if there are specific areas (processes, chapters, PM concepts, calculations, etc.) that you may want to revisit.
I personally did not use Rita's book when I prepared for my exam but many students recommend it. I, of course, highly recommend the PM Prepcast. Time may not permit this as it sounds as if you are close to taking your exam, at a minimum, I suggest that you read through the exam content outline again and make sure you are familiar with all the topics listed.
Best of luck with your preparations.
Yazmine Darcy, MBA, PMP, CSM
Senior Project Manager, OSP International LLC
The Project Management PrepCast™ -
www.project-management-prepcast.com