To get into Military Nursing Service or B.Sc.(Nursing) course of 4 years, an entrance exam is held every year (for females only).
For the year 2020, the date of application and fee submission was from 14 Nov 2019 to 02 Dec
Based on similar trend, for the year 2021, the dates might be in Nov-Dec 2020.
For eligibility and further details, check the official website
Hope this helps,
All the Best.