Hello Shahsi,

OBC certificate is not required while applying for the JEE Main application.

Although, you can get that prepared as it will be required at the time of counselling and admission in the any institute in your preferred degree course. At the time of document verification, you will be required to present your OBC Certificate which must be made within 6 months. And, after 6 months you will be required to get a new one made. So, it would be better rather than getting one made now, apply for the OBC Certificate after February, 2019.

Please comment below for further assistance.

All the best!