5.95 'on' for short periods of time
If you want to mention the day when something happens, you use 'on'. You can do this with named days, with days referred to by ordinals, and with days referred to by a special term such as 'birthday' or 'anniversary'.
- I'll send the cheque round on Monday.
- Everybody went to church on Christmas Day.
- I hear you have bingo on Wednesday.
- Pentonville Prison was set up on Boxing Day, 1842.
- He was born on 3 April 1925 at 40 Grosvenor Road.
- ...the grey suit Elsa had bought for him on his birthday.
- Many of Eisenhower's most cautious commanders were even prepared to risk attack on the eighth or ninth.
- ...addressing Parliament on the 36th anniversary of his country's independence.
You can use 'the' with named days for emphasis or contrast, and 'a' to indicate any day of that name.
- He died on the Friday and was buried on the Sunday.
- It is unlucky to cut your nails on a Friday.
You also use 'on' with 'morning', 'afternoon', 'evening', and 'night' when they are modified or qualified.
- ...at 2.30 p.m. on a calm afternoon.
- There was another important opening on the same evening.
- When she arrived at the court on the morning of the event, her voice had vanished.
- It's terribly good of you to turn out on a night like this.