If the Secretary determines that the final order developed with respect to an agricultural commodity is consistent with and will effectuate the purpose of this subchapter, the Secretary shall issue the final order. Except in the case of an order for which an initial referendum is conducted under section
7417
(a) of this title, the final order shall be issued and become effective not later than 270 days after the date of publication of the proposed order that was the basis for the final order.