I have taken the JEE books. From which subject should i start? I am tensed about JEE.

Start with the subject you have interest in. When you begin to gain confidence, shift to other subjects. Once you reach a point when you know what subject is you strength and which one the weakness, give more time to the weak subjects. Dont be tensed. Just study hard and religiously. All the best.

First priority is given to the chemistry, you will read NCERT books about chemistry and physics and mathematics, and you will solve other books.