This Act comes into effect as of the day on which 20 days have elapsed from the date of promulgation; provided, however, that the provisions of Article 2 and Articles 4, 5 and 6 (limited to the part of the provision amending Article 5, paragraph (1), item (xv) of the Act for Controlling the Possession of Firearms or Swords and Other Such Weapons (Act No. 6 of 1958) that adds "or a disposition extending it under paragraph (9) of that Article" after "order") of the Supplementary Provisions come into effect as of the day on which six months have elapsed from the date of promulgation.