These regulations may be amended, upon recommendation of the Planning Board, after public hearing and approval of the Town Board. Notice of the time, place and purpose of such hearing shall be given by publication in the official Town newspaper at least five days prior to the date on which it is to be held. A copy of the proposed amendment shall be placed on file in the Office of the Town Clerk, where it shall be available for public inspection during normal working hours for a period of at least five days before such hearing. Amendments recommended by the Planning Board shall take effect on the date of Town Board approval, or at such time as provided in the resolution of approval, and shall apply to any preliminary subdivision which has not received approval or approval with modification prior to such date, and to any preliminary subdivision approval, with or without modification, for which a formal application for final approval is not received within six months of the date of such approval.