(a) Each local governmental entity shall establish procedures whereby each payment request or invoice received by the local governmental entity is marked as received on the date on which it is delivered to an agent or employee of the local governmental entity, or of a facility or office of the local governmental entity.
(b) If the terms under which a purchase is made allow for partial deliveries and a proper invoice is submitted for a partial delivery, the time of payment for the partial delivery must be calculated from the time of the partial delivery and the submission of the payment request or proper invoice in the same manner as provided in section 3293.