Hey there.

For giving NDA exam, the candidates age must be between 16.5 years and 19.5 years. According to your birthday,  you will be eligible to give NDA after the December of 2022 as you will turn 16.5 years .

However, for more NDA relatdle information regarding the eligibility criteria, cutoff and latest updates, click on the link mentioned below

https://competition.careers360.com/articles/nda-eligibility-criteria

Hope this was helpful.

Thanks