NDA-1 and 2, is already over and the results for NDA 2 is expected to be declared in the November- December month.

As per NDA eligibility criteria, one must be not more than 19.5 years of age. You can apply after 12th class for NDA exam.

There are physical requirements as well. You need to be physically and mentally fit.

Further eleigibility criteria you can check here .

You can expect NDA- 1 forms in the month of Jan 2018.

Good Luck!