Your All India Rank is approximately 286773 going by the formula 100-67*869010/100 where in 67 is your percentile and 869010 is the no.of Candidates who appeared for JEE Mains in January session. Admission to IIST is through JEE Advanced scores and to be eligible for JEE Advanced, you will need atleast a percentile of 85 and above. So you will have to appear for July session. You can check the cut offs for IIST for the past years at our page: https://engineering.careers360.com/articles/iist-btech-cutoff . You can also prepare for JEE Mains with the  help of our Knockout package: https://learn.careers360.com/knockout-jee-main-april/