The number of days that it takes for bread to mold depends on several factors, including how it is stored, what ingredients were used to make the bread, and its "best by" date. Packaged bread can typically last for three to five days beyond its "best by" date without molding.
Bakery bread typically lasts two to three days beyond its printed "best by" date. Bread that is beyond its "best by" date should be well examined before eating, and if any mold is detected, the entire loaf should be discarded. If bread is hardened, but not moldy, it can be made into croutons for later use.