(A) In all cases where an ordinance or code provision 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 shall fall on a Sunday or a legal holiday, it shall be excluded and the next business day shall count as the last day.