Hi

You don't need to worry at all even if you have applied for only march and april session and want to appear in April session as well.

This is because,

One will have opportunity to apply again for the remaining March/ April /may  Sessions as application window will be re-opened for these sessions

For example,

the application Window will be reopened just after the declaration of February session results and that time one can apply for March session and the rest of the sessions as well, similarly application window will get reopened after march session results and that time one can apply for April session and May session also . Finally application window will get opened for the last time after April session results and that time one can apply for May session.

So, you can apply for April session when application Window gets opened after the declaration of February session results or you can even apply for April session when application Window gets opened after March session result

And,
When a candidate appear in more then one sessions then the best performance out of the attempted sessions will be considered for admission i. e if you appear in all the 4 or 3 or 2 session of Jee mains, then your best score out of these attempts will be considered for your admission process

Also,
There's a change in your jee mains examination pattern .In your jee mains 2021 paper -1 , there will be 30 questions in each of physics chemistry and mathematics . Out of 30 questions in each subject ,20 questions are MCQs and rest 10 questions are questions with numerical value as the answer , out of which only 5 questions are to be attempted.

Now , limited time is left for your jee mains 2021 examination, so focus on preparation, go through the chapters , practise questions and then revise them, go through mock test papers once you are done with complete syllabus.

For detailed information, you can visit our page at

https://engineering.careers360.com/articles/jee-main-application-form

Thankyou