The time within which an act is to be performed under the rules of this Chapter shall be computed by excluding the first day and including the last. When the last day for the doing of an act required by the rules falls on a Saturday, Sunday or legal holiday, then the required act may be performed on the next regular business day. The State Fire Marshal, for good cause shown, and with notice to all interested parties, may extend any time prescribed in the rules.
Okla. Admin. Code § 265:3-3-3