At atau On an article special day?

Everybody has a special day. How do you use an article an/a for it?

Oke. There is a Mother's Day and Christmas. Both are special days. But the differences between Mother's Day and Christmas is a word "day".

We use "on" for the special day uses a word day such as Mother's Day, Teacher's Day, Valentine Day etc.

We us "at" for the special day without a word "day" such as Christmas, Idul Fitri, Idul Adha, Isa Almasih etc.


Extra English

Talking about time, of course there is minute, hour, o'clock.
How do you say this time: 11:13 and 15:20

Oke.
First  Thirteen minutes past eleven
Second Twenty past three/fifteen 

Do you see the differences between the two sentences?

You are right, first sentence uses a word minutes and the Second does not use a word minute
Remember: the use minutes are 1,2,3,4,6,7,8,9
the minutes 5,10,15,20,25,30,35,40,45,50,45 does not use a word minute.

Thanks