On the third Friday of each month.

The option contract stipulates a specific exercise date, which is the third Friday of each month. In the United States, the exercise date of standardized stock options contracts is the third Friday of each month. For example, if the first trading day of a certain month is Monday, the third Friday of that month is the exercise day. The first trading day is Tuesday or the day after, and the exercise date is the day after the third Friday.