Written statements can only be made on sitting days. Sitting days are days when the House is meeting. You can see the list of written statements being published that day in the Order Paper.
Written statements are usually published from 9.30am onwards.
Departments must give advance notice to the House of their intention to make a written statement. In a new session, the earliest point notice can be given is the day of the King’s Speech. The statement can then be made the following day.