IIT JEE prepration minimum take one year.The complexity of the IIT-JEE arises from the fact that the questions are always unique in their context, and solving them often requires a combination of concepts from across different chapters. and to understand these concepts you must give time.
More hard work u will do ,better rank u will get.first thing to crack IIT JEE is hard work.
besides this you also need perfect guidence,best study material and books.
Please note that the JEE is not about scoring 100% in a subject or the examination. Your aim should be to attain an optimal score in each subject, depending on your strengths and weaknesses.
Just stay calm and focus on understanding rather than mugging. Be regular in class and stay with conceptsPlease feel free to post as many doubts on our discussion forum as you can.If you find any question Difficult to understand - post it here and we will get youthe answer and detailed solution very quickly. We are all IITians and here to help you in your IIT JEE preparation.All the best. Regards,Askiitians ExpertsBadiuddin