I did the same kind of thing, I gave myself three weeks to prepare because I thought any more than that would just encourage procrastination.
What helped me the most with it, and it may sound silly was just getting down solidly the break downs of math. What multiplies into what, what divides out etc. I felt like it really freed up my time to focus on questions that I needed to be more analytical.
Just my thoughts
Feel free to read about my progress