Hello!!

Hope you are doing great!!!

As per the previous year scenario,On an average the All India Rank for EWS category students should be around less than 3000.You may have to get around 200+ marks approximately in jee mains.Your percentile should be >99 approximately.But do note that the cutoff's may vary from year to year.You can check the previous year Cutoff's for top NIT's in the link provided below:

https://engineering.careers360.com/articles/jee-main-cutoff-for-top-nits

Hope it helps!!!