Dear nineet
 you have completed your syllabus. so from now you should give more stress to those topics in which you feel difficulty. or in which you are not much confident.and at the same time you should keep revising other topic also.Try to solve new question.
while revising you must complete all the concept of that chapter,previous IIT JEE question based upon that topic,questions from your study material,and Solved and unsolved question of the  text book you are following.
I will suggest you to join any test series.wher you can compair with others.and also you will know the possible changing pattern of IIT JEE as well as you will learn how to use your 3 hours in attempting the different portion of the paper.
once you start scoring good score your confidence level will increse.
you can join online test series it will save your time
Just stay calm and focus on understanding rather than mugging. Be regular in class and stay with concepts.

Please 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 you the 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 Experts
Badiuddin