Hey sujeet! 

I think it's highy suggestive to attend the 1st paper of jee and then of your qualified then you may be able to attend the 2nd paper of jee advanced.

Because the NTA would determine your percentile by taking the best out of both percentiles acheived in your 1st and 2nd jee exam papers

And also the qualification for the 2nd jee Advanced paper is 70 percentile. 

Wish you all the best!