Determining realistic delivery times is difficult for make-to-order manufacturers, especially due to uncertainties such as future production capacity utilization. Nevertheless, delivery times have to be stated in new offers. In this paper, we show a simple procedure for determining delivery times using the throughput diagram and determining a likely future situation by including early available information such as the acceptance of offers in the planning process. In a first simulative evaluation, the procedure is examined for its basic effect on the order lateness.