To create a pre-order (future order) via operator app first of all make sure that this feature is enabled. Proceed to My Hub "Services" tab and check the status of pre-orders feature (Instant or Delayed broadcast should be enabled).
Now while creating an order via operator app simply click on the date&time's fields and choose the details of pre-order. You can either type the required date & time manually or choose it in the calendar/drop down menu.
Pre-order can be done from 15 minutes in advance. You can change the minimum period for pre-order in the general settings of a service in the range from 15 minutes to 96 hours (available only if Instant orders are disabled for a service).
Pre-orders can be found in the “Pre-orders” tab in the left part of the screen. "Clock" is a special sign for pre-orders in operator app.