California Code, Civil Code - CIV § 1689.15

Notwithstanding any other provision of law, a contractor who is duly licensed pursuant to Chapter 9 (commencing with Section 7000) of Division 3 of the Business and Professions Code may commence work on a service and repair project as soon as the buyer receives a signed and dated copy of a service and repair contract that meets all of the contract requirements specified in Section 7159.10 of the Business and Professions Code.  The buyer retains any right of cancellation applicable to home solicitations under Sections 1689.5 to 1689.14, inclusive, until such time as the buyer receives a signed and dated copy of a service and repair contract that meets all of the contract requirements specified in Section 7159.10 of the Business and Professions Code and the licensee in fact commences that project, at which time any cancellation rights provided in Sections 1689.5 to 1689.14, inclusive, are extinguished by operation of law.