Shipping policy about multiple items

If a buyer purchases several PCB prototypes from you, and one of them is ready for shipment before the others, how is shipping handled ? All goods are shipped togheter in one package when the other prototypes are also produced ? or multiple packages are shipped uncombined ? It is important to know this for custom clearance issues. For me it is much more confortable and economical for the order to be shipped in one combined package and one combined invoice. Thanks.