As soon as practicable after the date on which a petition is filed under section
2401a of this title, but in any event not later than 40 days after that date, the Secretary shall determine whether the petitioning group meets the requirements of section
2401a
(c) or (d) of this title, as the case may be, and shall, if the group meets the requirements, issue a certification of eligibility to apply for assistance under this part covering agricultural commodity producers in any group that meets the requirements. Each certification shall specify the date on which eligibility under this part begins.