A. Unless otherwise specifically provided, the time within which an act is to be done under the Development Code shall be computed by excluding the first and including the last day. If the last day is a Saturday, Sunday, or legal holiday, that day shall be excluded. When the period of time prescribed is less than seven days, intermediate Saturdays, Sundays, and holidays shall be excluded.

B. Unless otherwise specifically provided, whenever a person has the right, or is required, to do some act within a prescribed period after the service of a notice or other paper upon him and the notice or paper is served by mail, three days shall be added to the prescribed period.