Computation of the 90 day period of time mandated by Section 150.30(f) shall begin with the first day following the day on which the complaint is filed and shall run until the end of the 90th day, or the next following business day if the 90th day is a Saturday, Sunday or State holiday as defined in Section 1-6 of the Election Code.
Ill. Admin. Code tit. 26, § 150.40