The Council shall every year hold an annual general meeting of the Institute to elect its members under clause (a) of sub-section (2) of section 12, or to discuss any matter which it deems fit, and not more than fifteen months shall elapse between the date of one annual general meeting of the Institute and that of the next:
     Provided that from the appointed day the Institute may hold its first annual general meeting within a period of not more than eighteen months and if such general meeting is held within that period, it shall not be necessary for the Institute to hold any general meeting in that year:
     Provided further that the Central Government may, for sufficient reasons, extend the time within which any general meeting shall be held.