Rishabh, NTA clearly mentions that what you enter in the Application form is completely in your jurisdiction and NTA will neither entertain nor make any corrections in the application form at any cost.  Which means that by any chance if your EWS certificate doesn't come through you will not be considered under General Category. You will be still considered as a Candidate belonging to EWS Category. And if you fail to submit the relevant document during document verification your admission might stand cancelled. Having said this, as you said that your EWS certificate might come in March and the exam is due in June, you still have time to get the certificate done. You will need the certificate atleast by the time of counselling and document verification.