A system and method schedule manufacturing of a product by a requested availability date. Sources of supply are selected for a given material to be used for manufacturing the product. A check is then performed for each source of supply to ensure that a valid-to date of the source of supply is equal or later than a plan start date. Lead times for sources of supply are calculated having a valid-to date equal or later than a plan start date. A source of supply is selected as a function of a validity interval of the source and a validity date.