28 CFR § 76.8 - Time computations.
(a) Generally. In computing any period of time under this part or in an order issued hereunder, the time begins with the day following the act, event, or default requiring service, and includes the last day of the period unless it is a Saturday, Sunday, or legal holiday observed by the federal government, in which case the time period includes the next business day. When the period of time prescribed is eleven (11) days or less, intermediate Saturdays, Sundays, and holidays shall be excluded in the computation.
(c) Computation of time for service by mail. Whenever a party has a right or is required to do some act or take some action within a prescribed period after service of a pleading, paper, or notice and the pleading, paper, or notice is served upon the party by mail, three (3) days shall be added to the prescribed period.