How do I delay posting an announcement until a specific date in a course?
You can set new announcements to post at a certain date and time.
Note: If you create an announcement in an unpublished course, the delay posting date must take place after the course has been published for notifications to send to those who have chosen to receive notifications for new announcements.
Type a title for the Announcement in the title field  and add content in the Rich Content Editor . Click the Delay posting checkbox .