Why is the anniversary of Our Lady appearing at Medjugorje celebrated on June 25th instead of June 24th, the first day the children saw the Virgin Mary?

On June 25, Medjugorje will celebrate the 40th anniversary of the first of the continuing apparitions of the Blessed Virgin Mary that began there on June 24, 1981.

Many ask: but why will they celebrate the anniversary on June 25?
 
On February 2, 1982, one of the visionaries asked Mary, “When must one celebrate the feast of the Queen of Peace?”

She smiled and answered, “I would prefer that it take place on June 25 th . The faithful have come for the first time on that day, on the hill.”
 
Mirjana Soldo, one of the visionaries at Medjugorje, said that St. John Paul II told her:
“Medjugorje is hope for the entire world. And if I were not Pope, I would have been in Medjugorje a long time ago.”

Mary revealed ten secrets to Mirjana. She told me in my interview with her, “I don’t want to talk very much about the
secrets, because secrets are secrets. I want to say one thing that is very important. 

Blessed Mary said, ‘What I started at Fatima, I will finish in Medjugorje. My heart will triumph.’ If the heart of our mother will triumph, we don’t need to be scared of anything. It’s only important to put our life in her hands and not to think about
secrets. We should think about the messages and what she asked for us, so that we can help her Immaculate Heart to triumph.”
 
Father Livio Fanzaga, Director of  Radio Maria in Medjugorje, said “I believe that the time of secrets coincides
with the 40th  year of appearances.”