To get into IITs is dream of many students. It is one of the prestigious college. 

You have enough time to crack your exam but you need to plan your preparation to score good marks as there is lot of competition to get into IITs.

To crack IIT-JEE you can refer below points-

1- You should refer NCERT books to start your preparation. Make sure your basics are clear. Don't use much reference books. You can use good recommended books for your preparation. 
2- You can use previous year papers to understand the exam pattern and level of questions.
3- You can solve as many as MCQs for your practice and to build up speed and accuracy. You should solve short-answer questions, subjective-type problems and questions based on assertion reasoning to develop deep understanding of the subject.

4- Try to give extra attention to the topics which carries more weightage in the exam. 

Be dedicated and self motivated to acheive your aim.

All the Best!!