Kuhnjm:
I would advise against even doing any NINJA MCQ until you finish the entire CPAExcel course. NINJA is broken down by the five AICPA categories so it can be difficult to only see questions that you have already covered in CPAExcel or Becker. As a result, you get a lot of questions that you simply haven't studied yet.
Seeing as you have 64 days until your exam, I think you will have plenty of time to drill through NINJA after completing the CPAExcel review course. From my own experience, I started Becker on October 6 for a November 23 exam. I completed F1-F10 in five weeks and then I was allotted two weeks to review. I didn't do a single NINJA MCQ until I had gotten to the review period and even after "only" 15 hours spent on NINJA, I have plowed through 1100 questions so far. My goal is to "see" every question on NINJA before Sunday, but we shall see!