Green (D) executed and signed a contract on June 10 for the purpose of obtaining re-roofing of their home. The document set out in detail the work to be done and the price to be paid in monthly installments. The agreement was to become binding only upon written acceptance by the principal or authorized officer of P or upon commencing performance of the work. This term gave P the opportunity to check out D's credit as the work was to be done entirely on credit. D knew the work would not start until the credit check had been done. D's credit was approved and on June 18th P engaged its workmen and two trucks and proceeded to D's residence to perform the work. When they arrived, they found another contractor at work performing the re-roofing. D forbade P to perform the work. The trial court found for D in that their offer was never accepted by P and hence no contract existed. The trial court ruled that D's notice to P was timely. P appealed.