Where the clinical establishments in respect of which standards have been notified by the Central Government, provisional registration shall not be granted or renewed beyond,—

   (i)  the period of two years from the date of notification of the standards in case of clinical establishments which came into existence before the commencement of this Act;

   (ii)  the period of two years from the date of notification of the standards for clinical establishments which come into existence after the commencement of this Act but before the notification of the standards; and

   (iii)  the period of six months from the date of notification of standards for clinical establishments which come into existence after standards have been notified.