The NDA 1st Examination was to be conducted on 19 April, 2020, but now it is being postponed due to the spread of Novel Coronavirus. There is no official notification till now, but the tentative date for conduction of this exam is 14 June, 2020.
Till then let's hope that India contain this COVID-19 Epidemic very soon and everything comes back to normal.
Refer here for regular updates - https://competition.careers360.com/articles/nda
Feel free to ask doubts in the Comment Section.
I hope this information helps you.