Dear aspirant;

Yes it is better to drop one year if you are  preparing forJEE mains exam.

Here are some tips;

For JEE main, yep NCERT will be really useful. Other than that, try: 

1. HC Verma for physics

2. RD Sharma for maths

3. P Bahadur for physical chemistry

4. NCERT will do for organic and inorganic chemistry (along with some coaching modules if you can get them somehow)

5. This is really important: DO NOT FORGET TO DO PREVIOUS YEAR PAPERS AND SOME SAMPLE PAPERS BASED ON CURRENT FORMAT AND SYLLABUS. It helps a lot. Really.

it will be a really daunting task to finish off your preparation in 5 months alone because if you haven't had the motivation to start preparing till now, then it is going to be so tough, trust me. 

Now lets plan your schedule so that you can finish all of the above in time (if you can finish all of the above books easily and master them, and also get a 90%+ score in board exams, then you, my friend are a stud. If DTU or BITS is your dream college (assuming you are from Delhi), then nothing will be able to stop you from getting an admission there).

Try finishing up NCERT, HC Verma, RD, and P Bahadur in just 3 months and no more than that. Then solve all of the sample papers and set aside the last month for revision. Do this and I don't see how you won't be able to score big. 

Thank you.