hi,

see JoSAA 2020 Registration and Choice Filling  will be started from October 06, 2020, however till now there is no Information for the ews certificates dates and issuing times. I suggest you to wait for josaa counselling notifications which would be update soon. however to register for jee advance exam, you have to upload a ews certificate which has issued on april 1, 2020  or after before online registration for jee advance, if the certificate is no available then you have to upload a  declaration certificate  in Lieu of GEN-EWS Certificate) to that effect.

You may use Careers360 college predictor tool to know your predictable colleges

https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer