How to create a time variable delay with 3 signals

You may user a C block and write the code.

The information about C block in PSIM can be found by clicking "Help >> Index", and then, searching for "C block".

There are example circuits, online help documents, and video tutorials.

To add to Rhonda's comments, this is tricky if you are doing an analog waveform, if you are doing a logic level signal you can use a comparator with an integrator to track time. then use some other logic elements like flip flops and logic gates to implement your delay.