A firm decides to go to the project based on its investment analysis. However, the cash flows generated from the real project can not be always coincident with what expected as it follows uncertain behavior and the asymmetric payoff caused by the managerial flexibilities involved in the real asset affects the project value. Amongst various managerial flexibilities entailed in most of the real assets, although investment delay has been known to enhance the project value thanks to its ability to provide new market information to management, the related research to select the time to invest have been just few. Therefore, this research aims to show the theoretical framework to decide when to invest reflecting the behaviors of increasing project value and loss recovery cost due to investment delay with option pricing, related financial economic, and variational theories.