A magistrate may continue the holding of a trial or hearing as provided in the supervisory rules of the Supreme Court of Appeals. In criminal proceedings when the defendant is in custody, the state shall not have the right to a continuance but may be granted a continuance for no more than five days if good cause is shown. In criminal proceedings when the defendant is in custody, the magistrate may continue the matter no more than once on his own motion over the objection of the defendant and such continuance over the objection of the defendant shall not be for more than two days.