establishment period

For purposes of this subsection, the term “establishment period” means, with respect to any State, the period beginning on December 28, 1973, and ending on whichever of the following dates first occurs: (A) the date of the close of the 120-day period following the adjournment of the first regular session of the legislature of such State which commences after December 28, 1973, or (B) the date of the close of the 15-month period following December 28, 1973.