When an election is made to place amounts reserved under chapter 38, Laws of 1970 1st ex. sess. (RCW 60.28.010), in escrow, the state agency jointly with the contractor and the escrow agent shall execute an escrow agreement according to Form A-39, Budget and Accounting Manual, or some other form approved by the attorney general's office. A copy of the completed escrow agreement shall be provided to the escrow agent, the contractor and the state agency prior to the time the first progress payment is made.