(b)In the case of an officer who receives notice of transfer at his headquarters during a vacation the question arises whether the period of notice is adequate. Adequate notice should be taken to mean the number of days to which the officer would have been entitled as joining time in ordinary circumstances. For instance, if he would ordinarily have been entitled to 9 days' joining time and received notice of this transfer 6 days before the end of the vacation, he will be entitled to 3 days' joining time after the close of the vacation.