Should I start my preparations for CAT from now? Which is better, self study or classes? As my graduation will be completed in 2018.

I think self study is all that is going to matter. You can try out the study material from IMS / TIME / Career Launcher as your first resource. Some of the Books recommended for CAT are- 1.How to prepare for Data Interpretation for the CAT   TMH / Arun Sharma 2.Pearson Guide to Quantitative Aptitude

Hi Akshar, You can start you preparation from now onward like your basis should be clear. Like CAT exam has mostly 10th maths so right now you can do self study and start coaching in year 2017. And I think coaching is a necessary for MBA preparation. One until and unless attend some coaching classe