A private applicator certificate shall be issued for a period of three years except that the initial term of a private applicator certificate shall expire as follows:
(a) Certificates issued to private applicators on or after January 1, 1997, with surnames beginning with A to H, inclusive, shall expire on December 31 of each third year following December 31, 1997.
(b) Certificates issued to private applicators on or after January 1, 1997, with surnames beginning with I to Q, inclusive, shall expire on December 31 of each third year following December 31, 1998.
(c) Certificates issued to private applicators on or after January 1, 1997, with surnames beginning with R to Z, inclusive, shall expire on December 31 of each third year following December 31, 1999.