How to make your lightbox form auto-popup on the screen after a period of time?

Your lightbox form can be triggered to pop up on the screen after a period of time of your choice. The user doesn’t need to do anything; the form will simply show up on the page in a lightbox.
In order to set up this form behavior, go to the Publish → Embed Code section of your form. In Lightbox click on Customize  to add the number of seconds you want to pass before the popup is triggered. Next, copy the code within the box and paste it in the code interface of your webpage.