Unless the Administrator otherwise explicitly provides in a particular promulgation, approval, or action, the time and date of such promulgation, approval or action for purposes of the second sentence of section 307(b)(1) shall be at 1:00 p.m. eastern time (standard or daylight, as appropriate) on (a) for a FEDERAL REGISTER document, the date when the document is published in the FEDERAL REGISTER, or (b) for any other document, two weeks after it is signed.
40 C.F.R. § 23.3