After the filing of a nominating petition by or on behalf of a candidate for membership on the board, the candidate shall not be permitted to withdraw unless a written notice of withdrawal, signed by the candidate, is served upon the official with whom the nominating petition was filed or his duly authorized agent not later than 4:00 p.m. of the third day after the last day for filing the petition unless the third day falls on a Saturday, Sunday or legal holiday, in which case the notice of withdrawal may be served on the official or his duly authorized agent up to 4:00 p.m. on the next secular day.