No contributions to the retirement system shall be made by a state agency or by any members prior to the commencement date as set forth either in paragraph (9) or (10) of Code Section 47-2-1, except for the contribution of the state agencies to an expense fund in order to pay the expenses of setting up and operating the retirement system prior to that date. The board of trustees shall notify all employers, and the employers shall notify the members, that contributions shall commence on that date. The provisions of this chapter regarding such contributions will go into effect on that date. In determining the commencement date, the board of trustees shall be governed by the money made available by the state to carry this chapter into effect.