Took 13 days on C960 and I think it can be shorter with some better strategy. There are 6 chapters in the course, and the most challenging part for me is the pseudocode questions.
Ch1: Algorithms, Ch2: Number Theory and Cryptography, Ch3: Recursion and Induction, Ch4: Counting, Ch5: Probability, Ch6: Modeling Computation
Zybook is still a good source and I used Ch1, 2, and 6. The pre-assessment and the OA are aligned and slightly easier than the Zybook and the exercise questions you can find. You can find tons of resources for learning these topics on Youtube so just learn what you need to know by the pre-assessment questions.
If I could start over, I would go for the pre-assessment right away, and I would know to focus on Ch1 and 2 for me and learn Ch6 at a much faster pace.