hi,

see nits admission for btech course is done by jee main score and you can attempt jee main by 3 consecutive years starting from your passed year of 12th exam, since most of the companies allow 2 year education gap, so you will not face problem during placement,. there is many companies who wants talented candidates , who knows technical subjects and programming very well,

so right now you dont need to worry so much, just focus on your exam.