Hey,

Trust me when I say this it's far easy to prepare well in both the examination.

As you are new to your foundation class (11th and 12th) you will have two complete years to prepare for your JEE nains exams.

Just figure out a proper approach.

I would suggest start from your basics that includes all questions that comes in your board examination (theory, proofs, numerical) . Refer ten years paper of Class 12th for this.

Now from the basic try to move to advance level that includes question coming in your JEE mains exam.

Scale a time table and move from your basics to advance. Keep on revising your chapters on regular basis.

Try practising proving as per your questions asked in Boards.

All the very best.

Thank you.