Assistance may be made under this subchapter only if the grantee certifies that it is following—
(1)a current housing affordability strategy which has been approved by the Secretary in accordance with section
12705 of this title, or
(2)a comprehensive homeless assistance plan which was approved by the Secretary during the 180-day period beginning on November 28, 1990, or during such longer period as may be prescribed by the Secretary in any case for good cause.