IIT has become a two phase exam so you have to plan accordingly. If you are already good at numerical solvimg skills, then you are half way through but if you do not have good numerical solving skills then you need to work hard.
If you have good numerical skills then you can target both IIT JEE Mains and Advance and if you do not have good numerical solving skills, I would suggest you to focus more on IIT JEE mains and boards part as that will lead you to a good NIT easily.
Coming to the preparation part, the theory can be understood within a few days, but when it comes to IIT, you need to have numerical solving ability both from a chapter and mixed chapters. Always prepare on a level above the level of exam. So you should start preparation in the following sequence.
1. Get IIT papers from the past 10–15 years of both AIEEE and IIT JEE. Analyze them properly and list a tentative weightage of each chapter. Also see the toughness level, language framing, numerical or concept based questions. After you are done with this make a list of topics based on their importance.
2. Get a mentor, guide or teacher who has good experience in teaching or who has cleared IIT with good rank.
3. Now divide your six months in two phases first one when you will go through all the chapters for the first time, second the revision time. I would suggest 4+2 would be the best.
4. Now plan the next 4 months. How much time you will take to learn each chapter(this you can discuss with your mentor or you can decide based on available material- lecture notes, theory books, question banks, video lectures)
5. You need to arrange complete content for the preparation as you will find it frustrating if you lesser content at your end while preparing. Apply for a good test series. You can also buy product from Topprr (), one of the best product available in market for practise.
6. Now start learning topics with proper practise, give weekly tests on your test series. (You can plan your prep according to test series) Analyze your performance regularly, work on your speed, effciency and numerical solving ability.
7. You performance graph should be positive(in case of low performance), if it is not positive then you should start working out harder and find out what problem you are facing, also discuss it with your mentor.
8. You should never loose hope and have confidence on yourself( it affects your performance a lot)
9. You should give your time more to highly relevant topics for IIT namely- thermodyamics, modern physics, electrostats and magnetics, mechanics, conic section, vector & 3D, calculus, gases, organicc chemistry.
10. After you are done with your course, revision and retention is must.
11. Last but not the least you will need to give 6–12 hours depending upon various factors- intelligence, knowledge, numerical solving ability.
Do it all and there will be fair enough chances of your selection. Even if you are not selected your life will go on and it won’t have any effect on your life. Just look for the second best option at that time.