Hi,
To crack IIT, you should focus more on your basics and solving maximum problems from each chapter to get a thorough knowledge. For doing this, you can join some of good JEE coaching institutes parallel with your studies, now or you can focus on your ISc now to get a good percentage of marks because for appearing JEE a minimum cutoff is required; then you can take a drop of one year and prepare for IIT.
Thanks & Regards
Robin
askIITian Faculty