They compute the Requested delivery date printed in supplier order emails sent from the Inventory Shopping List. With Days After Cutoff, Sprwt takes the order cutoff date of the first delivery date in the report range and adds the Delivery Window days (if no cutoff is found it adds the days to the delivery date itself). With Days Before Delivery, it subtracts the Delivery Window days from the first delivery date. A Delivery Window of 0 leaves the requested date equal to the delivery date. The email still says "As soon as possible" only when no date can be determined.