Three months is a workable window for CCAT if you structure it in phases rather than trying to cover everything at once.
Month 1 — Build the base
Work through each section's core topics once, without worrying about speed. Section A (aptitude/reasoning) and Section B (computer fundamentals) benefit most from early repetition since they rely on recall under time pressure.
Month 2 — Practice under conditions
Shift to timed practice sets. This is also when cheat sheets start earning their keep — you've already learned the material, now you're compressing it into fast-recall form.
Month 3 — Full mocks and gap-filling
Take full-length timed mocks weekly, and spend the rest of the week only on the topics your mock results show as weak. Avoid re-studying everything uniformly this late — targeted revision beats broad review in the final stretch.