See the SplashPopup menu in wp-admin to add the image and Date Time when to show the popup.
The popup will open automatecially when the page load, the duration of the popup is configurable in the wp backend,
you can chose the time slot when the popup image whil show in the front end.
The plugin code for the frontend will load on demand in the footer. meaning – if you inactivate it, it will not load any of its relating file in frontend.