Hey Saumyak,

To add to your knowledge, You can take CAT examination in any year of your graduation, but only the CAT exam taken in your final year will be counted as  valid. You could also write it any time after graduation suppose while working. But thing here is there should be no break, means you should either be working in a company/startup or you should be studying a recognized degree.

To be honest, there's no use of taking CAT exam in second year. If you really want to go in best B-schools. It is advised to take CAT in the final year of your degree. For now the best thing you can do is to start preparing for CAT, know the syllabus for CAT before hand. You have enough of time to cover whole syllabus before CAT exam.

Hope this helps!

Good luck.