Hello kaushal, as your dob is 20 March 2008 means you're turning 19 on 20 March 2028 , according to upsc rule maximum age is 19.5 year.

Since NDA conducted two time in a year and nda release their age criteria is born between 2 july 2008 and 1 january 2011

Without taking risk you're eligible for nda 1 and 2 in 2026, remember upsc is highly strict about their age criteria.