if you have not filled the form of JEE in 2019 i.e you have not filled the form 2 times of JEE and you have 75% in your 12th of CBSE boards or you are in top 20 percentile  of your respective boards, then you are eligible for JEE advance 2020. .

Hello,

Yes, you are eligible to apply for JEE 2020. You cannot directly attend JEE Advanced. In order to appear for Advanced you should score above cut-off in Mains. You can attend JEE upto two years after completion of Class 12. Also now you can appear for JEE twice a year, one in January and another in April.