The easiest way to validate integration is to go to Setup->Start and click the validate install button. You will also receive an email on success validation.
Go to Setup ->Activity Feed, leave the page open and then visit your website. Site events will show up on this page.
This is a more advanced solution and requires to open browser Developer Tools and check for the main script to be loaded and events to be sent under Network tab.
Filter using “vtcdn” keyword to show only our loaded resources. If you see nothing in here after you reload the page, then integration is not valid. Events are also available to view in here.