(a) Upon the written application to the board, any member of the fund who:
(1) Has attained the age of 60 years;
(2) Has completed 20 or more years of creditable service, at least 15 of which were service as a member of the Georgia National Guard;
(3) Served at least ten consecutive years as a member of the Georgia National Guard immediately before discharge; provided, however, for purposes of this paragraph, activation of a Georgia National Guard member into any of the regular components of the armed forces shall not constitute a break in service; and
(4) Has received an honorable discharge from the Georgia National Guard
shall be retired by the board on a retirement allowance and shall thereupon become a beneficiary of the fund.
(b) The effective date of retirement shall be the first day of the month in which the application is received by the board, provided that no retirement application shall, in any case, be earlier than the first day of the month following the month of the applicant's discharge from the Georgia National Guard. Applications for retirement shall not be accepted more than 90 days in advance of the date of discharge.