Typically we let our delivery partner decide how to best deliver the shipments to our customers, this way they can optimize their delivery trucks and personnel. We just need to provide them, before the 1st of the month, with a list of customers and their addresses, and each customer's choice and count - I should have mentioned that we give customers the ability to buy more than one of each month's selection. We also send our delivery partner a daily list of changes that includes a list of customers who have requested a specific delivery date... How do we know when the delivery is scheduled? Import an XML list from the delivery guys? Would it be better for us to deal of the (algorithmic) complexities of calculating delivery routes and such? Our customers can change at any time the delivery date? this is going to be hard because of lead times for the delivery people. How about just indicate the day(s) of the week and time frames when delivery should be made (e.g. morning aka 8am to 11am, noon aka 11am to 2pm, afternoon aka 2pm to 5pm and evening, 5pm to 8pm.) Allow the customer to change the specific day of the month when the delivery is made.