his coverage period shall begin on whichever of the following is the latest:
(A) July 1, 1966 ;
(A)#
July 1, 1966 ;
(B)#
the first day of the third month following the month in which the State agreement is entered into;
(C)#
the first day of the first month in which he is both an eligible individual and a member of a coverage group specified in the agreement under this section; or
(D)#
such date as may be specified in the agreement; and