Hi Vishnu,
Just starting the workflow won't populate the "Logged in User" field because the custom action doesn't work this way.
It would work if your workflow would get the user name, save it in a list and qListForm set to edit/display that list item.
But here is the approach I'd take, write a custom action based on the Visual Studio solution that we distribute with the product (see the QWP installation folder Sample Code directory) add your code to get the current logged user and use form initialization action to call this custom action and display that value.
Please check our documentation for more details about this topic. Also I responded to some questions regarding this in this forum.
Please let me know how it goes.