Engineering Entrance Exam

Hi,
For the candidates to qualify for the admission in the IITs/NITs/IIITs and such other CFTIs whose admissions are based on the JEE (Advanced) / JEE (Main) ranks, they should have secured at least 75% marks in the 12th class examination, or be in the top 20 percentile in the 12th class examination conducted by the respective Boards. For SC/ST students, the qualifying marks would be 65% in the 12th class examination. The states of Gujarat, Madhya Pradesh, Haryana, Uttrakhand, Nagaland, Odisha and some other institutions have joined JEE (Main) system. However, their admission criteria will be notified by the concerned authorities. Therefore, the candidates seeking admission to the institutions in these states, which were earlier admitting based on their state level examination, are also advised to fill in the JEE (Main)2017 application form online.
Candidates who cleared class 12th/qualifying examination in 2014 or before as well as those who will appear in such examination in 2018 or later are not eligible to appear in JEE (Main) 2017. Candidates who appeared in class 12th/equivalent qualifying examinations in 2014, did not clear in 2014, but passed in 2015 are also not eligible to appear in JEE (Main) 2017.
For more details, visit:
http://jeemain.nic.in/webinfo/Public/Home.aspx

Hello Chandramani,
It's good to hear that you have such a high ambition in your career. As you have set your ambition so high, so you should also be aware that you need to work really hard. You should understand the basics of physics, chemistry, mathematics and computers that you will be learning in class 11th and 12th.
You should ensure that your marks are above 80 percent in class 12th board examinations. Along with these, you also need to prepare for competitive exams. Books for preparations for IIT-JEE / AIEEE are easily available in the market. It is recommended that you join a good IIT coaching institute as well. They will help you to understand the concept better. They also take periodic tests which help you analyze how much are you prepared and how much more effort you need to put.
Then, you need to apply and appear for IIT-JEE Mains and IIT-JEE Advanced after completing your class 12th board examination and score good.
I wouldn't recommend dropping a year or so after class 12th board examinations for preparations for competitive entrance examinations.
However, I would also advise you to appear for other entrance examinations as well. This serves as a backup plan if things don't end up as per you had planned. You should also appear for AIEEE and state level examinations (COMEDK for Karnataka, EAMCET for Andhra Pradesh / Telangana, OJEE for Odisha etc.). The more the entrance examinations you appear for, the more options you will have for choosing colleges.
I hope it helps you.
If so, kindly upvote this answer. In case you have any further questions, feel free to revert.