Anjali ;

Getting a seat in an IIT is the most prestigious achievement for a student pursuing a career in engineering. Your preparation is most important here.

Now that you have around 6 months time , you can easily cover the whole syllabus if you study 6-9 hours daily. Give every subject 2-3 hours a day and you will do really good in advance. Solving problems every single day will be vital here.

First of all you need to get really good at physics. Physics is the most important barrier to get a seat in an IIT. Depending on your preparation, you can always score good in mathematics and chemistry. But, physics is most important here.

I would suggest you to solve mathematics from Cengage publication. It's very accurate in providing good questions. For time management, this book is best.

In chemistry GRB is preferable. If you spend enough time for chemistry, it'll help you score higher in JEE advance.

For physics, Arihant's  publication is really good and will help you score high marks.

Your time management will be really really important, you need to cover every chapter.  If you do so, you'll rock the advance exam.

Hope this helps and all the best!