The short answer is Yes.
The syllabus covered for CAT is very straightforward. Maths syllabus is equivalent to what is seen in 6th to 10th standard text book, and basic reading comprehension and sentence structures in English. The exam is tough because the questions are very application-intensive and because there are ~2 lakh people fighting for ~6000-12000 good seats
An aspirant can start by June, comfortably finish all the portions by August, or latest early September, take 20 mock CATs and be ready for CAT by November. This exam is as much about momentum and intensity as it is about knowledge or application. The intensity with which one prepares in the last lap will be a bigger determinant than how long you have been poring over basic formulae.
So, why do people start 12-months before CAT?
This trend of starting 12 or 15-months before CAT started recently. When I took my CAT, we guys used to start preparing in August (reluctantly). Now, I took my CAT in 2000 and back then the CAT exam was in December. But even adjusting for that, we guys used to prepare for barely 3-3.5 months. But we threw in a lot in that final lap. Many of my friends hit 30 mock CATs before the exam. Back then 70% of preparation used to be about taking practice exams. (Most of us would have been shocked if someone had asked us to prepare for percentages for 5 weeks)
The most important driver for this change has been the development (over-development) of the test-preparation industry. It really helps the industry if college-goers start enrolling themselves for courses 12 or 18 months before the exam. Less than 5% of this brigade takes the exam seriously. Any trainer will tell you that the longer term batches are the worst preparing. Students start missing classes and denude themselves into believing that they are geared merely because they started very early. 12 months into the course, the average attendance levels are less than 10% and when the time is perfect for starting preparation, these long-term and uber-long term batches lose all momentum.
I am starting preparation now, what should be the plan?
To start with, do not tell yourself you dont have a chance because you are starting late. Cover topic by topic for maths for the next ~8 weeks. Read something for at least an hour each day. Spend 2-4 hours each week on DI and/or LR. Run this schedule for ~ 8weeks during which time you should have also taken 2-3 mock CATs. In this first phase, do not worry about time pressure, speed, overall percentiles, etc.
By middle of August, you would have seen most question types, and covered most topics in quant. From here on, take one mock CAT every week and fill whatever gap areas you have. Identify gap areas based on your own gut feel and from what the mock CATs tell you. Have this as the plan for the next 6 weeks. During this phase, you should start building intensity. Plan part tests and exercises in short bursts. Mix up topics and ensure that you avoid concentration lapses. You should create a package like 10 questions in Number Theory, 3 selected passages from Economist, TIME and NYtimes, one DI grid and one LR puzzle from the web in 45 minutes and test yourself at breakneck speed. This phase is like strengthening muscle by muscle before a tournament.
Final few weeks, take mock CAT, review mock CAT aggressively. Repeat. Fill gaps if they still crop up and be as relaxed as possible.
I started preparation last November, what should I do now?
This is quiet simple. Restart now. Create a plan to aggressively ramp up intensity.