Hello, I hope you are doing well

There are many phases of a exam, which include the application form filling, exam itself and then the counseling process.

So, regarding your category certificate, it usually is not checked before the counseling process. So, if you are planning on getting a OBC-NCL certificate before the counseling starts, then yes you can.

Also, you can change it during the correction period if you want to. And, in the case where you don't have the latest OBC-NCL certificate, then you will be considered an general candidate and will be allotted seat based on general category.

Hope this helps.

All the best!