Quickbooks makes this possible. You can date the orders into the future (charging zero on those invoices), and if you're using the program to generate roast reports, those items will show up when they're supposed to. The initial purchase should be logged (for accounting purposes) as one item (maybe under "Service"), as if you were selling them a grinder or t-shirt, the day of the sale.
Hope that helps (if you're using QB). Good luck!