Wash. Rev. Code § 29A.72.030
Initiative measures proposed to be submitted to the people must be filed with the secretary of state within ten months prior to the election at which they are to be submitted, and the signature petitions must be filed with the secretary of state not less than four months before the next general statewide election.
Initiative measures proposed to be submitted to the legislature must be filed with the secretary of state within ten months prior to the next regular session of the legislature at which they are to be submitted, and the signature petitions must be filed with the secretary of state not less than ten days before such regular session of the legislature.
A referendum measure petition ordering that any act or part of an act passed by the legislature be referred to the people must be filed with the secretary of state within ninety days after the final adjournment of the legislative session at which the act was passed. It may be submitted at the next general statewide election or at a special election ordered by the legislature.
A proposed initiative or referendum measure may be filed no earlier than the opening of the secretary of state's office for business pursuant to RCW 42.04.060 on the first day filings are permitted, and any initiative or referendum petition must be filed not later than the close of business on the last business day in the specified period for submission of signatures. If a filing deadline falls on a Saturday, the office of the secretary of state must be open for the transaction of business under this section from 8:00 a.m. to 5:00 p.m. on that Saturday.
RCW 29A.72.030
Initiative, referendum, time for filing: State Constitution Art. 2 s 1 (a) and (d) (Amendment 7).
Petitions-Time for filing: RCW 29A.72.160.