Calendar days shall be used in all computations of time made under the provisions of this act. In computing time for any act to be done before any election, the first day shall be included and the last, or election day, shall be excluded. Sundays, Saturdays and legal holidays shall be included, but if the time for any act to be done shall fall on Sunday, Saturday or a legal holiday, such act shall be done upon the day following such Sunday, Saturday or legal holiday.