Dear aspirant

The age of applicant should be in between 16.5 to 19.5 yrs old.

For NDA 1 candidate's should have been born between  2nd July 2005 to 1st July 2008.

For NDA 2 Candidates should have been born between January 2nd, 2006 to January 1st, 2009.

So as you are now 15 yrs old by January 2024 you will be 16.5 so you can give both NDA 1 and NDA 2 in 2024.

Hope this was helpful for you

Good luck