You cannot say that is is bad or wrong. Many students take this step for their preparation. But I will suggest you to take this step only if you are confident enough to utilize this gap for your preparation. Otherwise it will hamper your year. In that case, you can join a college and meanwhile prepare for the entrance. 

As per the new jeemain guideline, you can appear for jee mains 3 times consecutively. So your decision and preparation has to be very sincere and systematic.

If you take a drop for preparation, take it, but work hard and sincerely to get what you aim for.

Have the basic understanding of all the important concepts and topics in your syllabus and paste it in front of you.

I hope you take a wise decision.

All the best.