Is it late if I start the cat preparations now.

You can definitely give 2017 a try,but honestly you have very limited time for Preparation, my personal recommendation is to attempt 2018 whole heartedly with full preparation. As of Now just brush up basics and give some 3-5 odd mock exams before CAT 2017. Also, you can give onljne mock tests on platforms like HitbullsEye, Oliveboard, TestFunda. If you score good enough, then its the best case. Incase you don't,you should aim for 2018 with 99percentile. Now, There are plethora of books available but byfar the best have been mentioned below. 1.How to prepare for Quantitative Aptitude for the CAT by Arun Sharma. 2.Pearson Guide to Quantitative Aptitude for CAT by Nishit Sinha. Moreover, recommended to go through TIME Coaching Institute Material for Logical Reasoning , Verbal Ability, Data Interpretation of solved examples and last 5year question sets for Quantitative aptitude. For Easy level problems, or for beginner level preparation you should go with Chandresh Agarwal and notes from CATKing Coaching classes where there is elaborate pattern. A minimum of 70 percentile in all sections and overall 80 percentile is mandatory for getting call from IIMs.

Yes, to be honest it is a bit late to start preparing. But you can still get a decent percentile. The trick is to give as many mock tests as you can.  I would recommend that you start giving mock tests and give as many tests as you can. Mock tests will help you to manage your time properly during exams and you will learn where you need to work upon.

Testfunda, olivevoard are two sites which have good test series and a lot of people give them so you get to know where you stand. You need to be very focused and devote most of your time to the preparation if you actually want go so well in cat if you are beginning preparation right now.

Its never late to start the preparation at any time. just you have to be specific while studying now. You have to sort out what you need to focus on and leave out the part you are already thorough with.