Click "Messaging" from the header menu.
Choose the listing group or specific listing you want to create the message for.
Click "Add Rule" in the top right-hand corner.
Click on the drop-down menu under "Event"
Choose "When Occupied"
Choose what day of the week you want to send a message on from the drop-down menu under "Day of the Week"
Alternatively, if your message is regarding trash you can choose "Take Out the Trash" from the templates drop-down menu and then edit the message as you'd like.