I will appear for jeemains in 2018 so where i will get the option for counselling in nsit? ? Do the option of NSIT will appear in jee main?
Around 240 marks will guarantee you a rank in under 3000 (considering that boards marks do not count), which is sufficient for a Delhi-General candidate to get CSE in DTU/NSIT. If you are outside Delhi general, consider getting half the rank, (~250–260 marks).
However anything above 200 (more closely, 210) will get you a rank under top 7000 which will get you IT in NSIT/DTU or Software in DTU.
Work harder, prove yourself! ALL THE BEST :)