Section 3A. Not later than seven days after a plea of guilty or after a verdict of guilty and in any event before adjournment of the sitting at which such plea or verdict has been taken and recorded in a case of felony wherein no question of law has been reported for decision by the supreme judicial court, the district attorney shall move for sentence; provided, that nothing herein shall preclude the district attorney from again making such a motion in any case where the imposition of sentence is delayed under section forty-seven.