Most valid way for the URL html structure

There are different ways to achieve this. Google tries to automatically extract the publish date of an article you wrote. The most common and easiest way for Google is to use rich snippets: http://schema.org/Article
See “datePublished” – property for this.

After you implemented these little HTML-snippets you can test your markup using the Rich Snippet Testing Tool: https://developers.google.com/structured-data/testing-tool/