As your Percentile is 77 and you belongs to SC category this means dear Student you have cleared Cutoff because Cutoff  for SC Category this year is 54 percentile. As you are saying that you want to get admission in NITS . But in my point of view your percentile is very less to take admission into NITS. You can predict it by College predictor link provided by Careers360.

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

Some of the NITs you can get are

1. NIT Kurukshetra

2.NIT Sikkim

3. NIT Arunachal Pradesh

4. NIT Meghalaya

5. NIT Raipur

And other NITs in which have Home State quota.

Thanks and Have A Very Nice Day