The comma is a grammatical sign of punctuation spread in the Latin alphabet, including English.
To apply it on specific dates, the following rule should be followed:
When writing a date, the comma is used to separate the day from the month, and the date from the year.
For example:
Semptember 11, 2001, was a sad day in US history.
I was born on Monday, Jun 14, 1990.
However, if you're writing the date in day-month-year format, you do not need to comma.
Example: Classes will commence on 1 may 2015.
