The first terms of office for the trustees provided for in subdivisions (d) and (e) of section five of this article shall expire June 30, 1965, June 30, 1964 and June 30, 1963, respectively, as the Governor shall designate at the time of the appointments. Thereafter, the terms of office for the said trustees shall be five years. Each trustee shall serve as trustee until his successor is appointed and has qualified. In order to make the preliminary arrangements for the operation of the retirement system as of its effective date, the Governor shall make the appointments provided for in section five hereof as soon as practicable after the passage of this article.