When you save the game you can save the time, which I assume is a global variable, into local storage. Whenever you launch the application (not the save file), you can check on start of layout if certain local storage values exist and display them, so if "savetime1" exists, you would display it in a text object under save slot 1 or something similar. "savetime1" existing just means you saved the game to slot 1 at some point and there is an elapsed time to load.