Okla. Stat. tit. 19, § 1258

Proceeds from sale of bonds - Disbursement - Payment of contractor. The proceeds from the sale of the bonds pursuant to the provisions of Section 1257 of this title shall be deposited in separate accounts established for each improvement and disbursed only for the cost associated with the respective improvement. Payment to the contractor shall be in parcels on the completion of the work or improvement or any part thereof, not less than one block, to an amount equal to the improvement so completed and accepted. Any funds not disbursed shall be utilized by the county commissioners to recall outstanding bonds. Payment to the contractor in money shall be paid no more than sixty (60) days after the due date for payment of assessments, including special assessments and each installment of such assessments and the interest on such assessments.