Hello,
NDA/NA is conducted twice a year in April and September. NDA I is conducted in April while NDA 2 is held in September.The notification of NDA 1 exam has been released along with the application form on January 9, 2019.NDA 1 application form is be filled from January 9 to February 4, 2019.
To check out the eligibility criteria, you can visit the below given link:
https://competition.careers360.com/exams/nda
Good luck.