Hello aspirant

I also face this situation during my Josaa counseling so that's why I am eligible to answer your query

If your category certificate is not ready then they provide you a option to fill self declaration form in which you have to mention that now the certificate is not generated by government and they gives you enough time to prepare your certificate and after that you try to make your certificate as early as possible.and then in the place of declaration form you have to submit your category certificate.