The Closing Rank in Round 6 of JOSAA for Home State Quota at NIT Trichy (General Category)-CSE, this year was 4.7k. So to be sure of a seat in NIT Trichy CSE, you need a Rank of Atleast 4k in JEE Mains, which roughly converts to a percentile of 99.6. For securing this score I believe you need to secure atleast 70% of the Total Score, or 200+/300.

So your first target should be to secure 60-70 atleast in each section of JEE Main and you should work accordingly to achieve your target.