This field in the Bin Label report (RBL) is only available when you select the Price Change File as the "File to Use." The purpose of this field is to allow you to add RBL to a daily queue to print labels for price changes whose effective date is X number of days away. For example, a daily RBL using the Price Change File with ‘Days before Effective’ set to 1 will print labels for price changes whose effective date is tomorrow.