You can enter a variety of schedule dates associated with a purchase.
When a purchase is created the date that the purchase was created on will be automatically recorded.
You can set other dates either before or after they occur.
For example if you are raising a purchase for someone else to process, you can set the Required by date to indicate to them when they need to complete the purchase by.
When a purchase has been placed, the Expected on date can be set to indicate when the goods can be expected in.