Acumatica does not a have Pre-Order date field on the Stock Item, but  if Pre-Order is part of your business processes you can easily solve it suing an Attributes at the Item.

But how to transfer it to the BigCommerce store? Here is the guide how can use use Commerce Entities mapping feature to map an Acumatica Attribute to BigCommerce API field:

The Pre-Order Release Date should have following formula:

=Year(CDate(eStockItem -> Attributes.Product Purchase Date]))
+'-'+Month(CDate(eStockItem -> Attributes.Product Purchase Date]))
+'-'+Day(CDate(eStockItem -> Attributes.Product Purchase Date]))
+'T00:00:00+00:00’

Also do not forget to define proper status on the e-Commerce Tab

After sync, you will be able to see that this field is populated in BigCommerce:

Hope it helps!