The date of Father's Day in Nepal falls in either in August (Shrawan or Bhadra) each year, depending on the cycle of the moon. The Bua ko Mukh Herne Din in Nepal runs for one day. As we all know that father's day is celebrated to respect the father.
For your kind information, in Nepal, Father's Day, Bua ko Mukh Herne din and Kushe Aunshi are the same. All meaning of them is similar.