In WA state - exactly WHEN does the 90 day window of opportunity begin and does it include weekends and holidays or mean just "B

In counting days, the general rule is that limits under 7 days do not include Weekends and holidays. Over 7 days it is calendar days. For liens, 90 days starts from your last day on the project, no including punchlist or warranty work. You count every day. The last day is the last date you performed work that was required to complete the scope of work required under the contract. My rule of thumb is to file the lien after 60 days so that if there is a mistake, you have a chance to correct or amend the lien if the law allows. Each state is different, but they all have one thing in common - Lien laws must be followed strictly. Consult a Washington attorney before filing.