There are multiple date fields associated with an order and most of them automatically get set appropriately during the normal entry, scheduling, and completion of an order.
If you are entering an order/invoice that was done in the past, then you want to be sure that these date fields are set appropriately. To do this, when you enter the new order, type in whatever date in the date field on the order and fill out the order normally.
Then when you change the status on the order to Done, be sure you go to the Date/Time tab of the Activity Details screen that will pop up and set the 3 date fields there appropriately. There is the Schedule Start Date/Time, the Actual Start Date/Time, and the Actual Finish Date/Time and all of those need to be set to the date in the past. Then your order will have the appropriate dates on it for reporting purposes.
