Your 12th percentage holds no importance in jee mains as long as you're eligible for the exam by having minimum percentile required. If you're a general category student you would have a rank around 50-60k with this percentile, though you can't get cse in NITs as being a core branch the cutoff for cse are high one needs to have a rabk below 15k to get cse in NITs. However you have options of private colleges that are affiliated to Jee mains you can easily get a cse seat in this with this percentile.

You can predict what colleges you might get with this rank by going through the link of college predictor tool given below.

https://engineering.careers360.com/jee-main-college-predictor

Thank you.