Hello Aspirant,

No, it is not compulsory to give JEE Mains April Exam if you have already given the JEE Mains which was held in January. You have the option to give either one of the exams or both, the better score of the two will be considered for the admission.

No, it is not necessary to give JEE Advanced to take admissions in NITs. Admission to NITs and IIITs is based solely on your JEE Mains score. And, a minimum percentage of 75% is required in 12th boards.So, if you have a good enough percentile (which in your case is 97.33% which is good ) in JEE Mains, you have a high chance of getting into a good NIT .

Hope this helps. Good luck!