Hi there,
Hope you are doing well.
In such cases, you would have been asked to submit a lieu of certificate at the time of form filling.
If your form would still not be available during the counselling session, then you would either be asked to submit an affidavit or an undertaking stating the reason and actions if you won't submit the form after the deadline that would be given to you.

However, it doesn't take much time to get an OBC-NCL Certificate.
Hope it would help.
Thank You