Sir I am planning for CAT. How can I change the plan to CAT?

First of all, all the best for your preparation. As your question is about study plan so you can simply Google it (it's always best), or ask any of your college professor that you trust. You can also download any good app for preparation for CAT exam, if you wish to do it yourself. There are many online resources available. Otherwise you can always buy a reputed book too if you want. If you wish you can also join classes. But better option would be preparing on your own. It's all up to you. All the best!

CAT need smart work. . .focus and concentration with proper planning know the latest pattern and syllabus through internet. . . and try to solve old papers so you can compare your level. . .you will find your weakness. . and then you have to focus on those sector. . . practice as you can... time management is the key factor. . . coaching or books or any other content is up to you. . .you can choose any thing that's suits you best. . . but self study can bring better result. . All the Best. . .