Neb. Rev. Stat. § 81-1378

(1) The dates indicated in sections 81-1379 to 81-1383 shall refer to those dates immediately preceding the beginning of the contract period for which negotiations are being conducted. (2) When any date provided in sections 81-1379 to 81-1383 falls on a Saturday, a Sunday, or any day declared by statutory enactment or proclamations of the Governor to be a holiday, the next following day which is not a Saturday, a Sunday, or a day declared by the enactment or proclamation to be a holiday shall be deemed to be the day indicated by such date. (3) The dates indicated in sections 81-1382 and 81-1383 are jurisdictional. Failure of either party to act in a timely manner shall result in a jurisdictional bar for either the commission or Supreme Court.