(A) In all cases where an ordinance requires an act to be done in a reasonable time or requires reasonable notice to be given, reasonable time or notice shall be deemed to mean the time which is necessary for a prompt performance of such act or the giving of such notice.
(B) The time within which an act is to be done, as herein provided, shall be computed by excluding the first day and including the last. If the last day is a legal holiday or a Sunday, it shall be excluded.