The time within which any act under these rules is to be done shall be computed by excluding the first day and including the last, unless the last day is Sunday or is a holiday as defined or fixed in any statute now or hereafter in force in this State, and then it shall also be excluded. If the day succeeding such Sunday or holiday is also a holiday or a Sunday, then such succeeding day shall also be excluded.
Ill. Admin. Code tit. 53, § 100.200