When placing an order an option is displayed to select an emergency drop, if enabled by the supplier you will be able to place an order for the same day.
This is controlled by each supplier via the allow emergency drop setting that is in the delivery schedule. The steps a supplier needs to follow to activate these settings are the following, this is also applicable for self managed suppliers.
Click Delivery Settings from the left.
Click Delivery Schedules.
Edit the required schedule.
Check the box for the permission Allow Emergency Drop and click Save Settings at the bottom.