(a) in the case of the subdivision of land, conditional approval of a final plat as the term is defined in section two hundred seventy-six of the town law, and approval as used in section 7-728 of the village law and section thirty-two of the general cities law;
(b) in the case of a site plan not involving the subdivision of land, approval by the appropriate body or office of a city, village or town of the site plan; and
(c) in those cases not covered by subdivision (a) or (b) above, the issuance of a building permit or other authorization for the commencement of the use, improvement or development for which such permit or authorization was issued or in those local governments which do not require such permits or authorizations, the actual commencement of the use, improvement or development of the land.