Hello Akansha,

Union Public Service Commission conducts combined defense service exam twice per year in order to sign on candidates for "Indian Military Academy, Officers Training Academy, Indian Naval Academy and Indian Air Force Academy". I will guide you with every little detail you need to know.

I. CDS OTA (Combined Defense Services-Officer Training Academy) till date conducts exam in traditional mode i.e pen-paper mode consisting of objective type questions to assess the English and General Knowledge (excluding mathematics) of an applicant.

II. OTA and IMA a candidate must have a graduation degree from a recognized university. INA requires an engineering degree  and AFA candidates must have an engineering degree  or have studied math and physics attheir intermediate level.

III. These books that i recommend you will build your base and carry you forward to achieve your goal (you can refer other books too after you understand the basic pattern of the exam)

1. High School English Grammar and Composition Key by Wren and Martin
2. Word Power Made Easy    by Norman Lewis
3. A Modern Approach to Verbal & Non-Verbal Reasoning by R.S. Aggarwal
4. Combined CDS (OTA) Book    by Defense Direct Education
5. Pathfinder CDS by Arihant Experts

Also read news papers and magazines to build your awareness.

So the answer to your question is a big YES, you can start your preparations from today and can apply for your exams once you complete your graduation degree .

ALL THE BEST!!