The § 14-1010 shall expire at the earlier of:
(a) 12 months after it became law; or
(b) certification by the Historical Commission to the Chief Clerk of Council that it has mailed notice of the proposed historic designation of more than twenty-five percent (25%) of the properties among the designated properties in the Victorian Roxborough area to the owners of such properties pursuant to § 14-1004 ("Designation").