First furnishing starts the 20-day period
Use the first day the claimant supplied labor, service, equipment, or material to the work of improvement. The contract date, invoice date, and date payment became late are different facts and should not replace first furnishing.
Late service has limited reach
Service after day 20 does not necessarily make the notice useless. Under Civil Code § 8204, the notice can cover work furnished during the 20 days before service and work furnished afterward. Earlier contributions may remain outside that reach.
Recipients depend on the claimant and project
A subcontractor or material supplier commonly serves the owner or reputed owner, direct contractor, and construction lender. Direct contractors and claimants on public works use different recipient rules. The job intake should preserve each recipient's statutory role rather than treating every address as interchangeable.
Service and proof belong in the same file
California permits specified delivery methods under Civil Code § 8110. FirstFurnish sends approved private-work notices by certified mail with electronic return receipt and stores the mailing identifier and tracking result with the job.