Hello
JoSAA counselling is conducted every year for admission in B.Tech courses in IITs, NITs, IIITs and GFTIs based on JEE Main and JEE Advanced ranks.
Important dates for JoSAA 2020 are;

• Registration starts: 6 Oct 2020
• Last date for registration: 15 Oct 2020
• First round of seat allotment: 17 Oct 2020
• Online reporting for round 1: 17 to 19 Oct 2020

So you need to upload documents and complete your registration by 15th October.

Follow this link for more information on JoSAA counselling https://www.google.com/amp/s/engineering.careers360.com/articles/josaa-counselling/amp

Follow this link to predict your college based on JEE Main https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer

Good luck