A special permit granted under this chapter shall lapse within six months of issuance, including the time required to pursue or await the determination of an appeal as allowed under MGL c. 40A, § 17, from the grant thereof, if a substantial use thereof has not sooner commenced, as determined by the special permit granting authority, except for good cause, or, in the case of permit for construction, if construction has not begun by such date except for good causes.