(a) In computing any period of time prescribed or allowed by these rules of practice, the day of the act or event from which the designated period of time begins to run shall not be included, except as otherwise provided. Saturdays, Sundays, and Federal legal holidays shall be included in computing any period allowed for the filing of any document or paper, except that when a period expires on a Saturday, Sunday, or Federal legal holiday, the period shall be extended to include the next following business day.(b) A prescribed period of time within which a party is required or permitted to do an act shall be computed from the time of service, except that when service is accomplished by mail, 3 days shall be added.