WordPress.org

The Timed Page/Post Content plugin is a marketing tool that allows users to specify that a portion of a Page or Post should appear/be visible or disappear/be invisible based on given time characteristics. Suppose, for example, you embed a video into a Post; once the viewer has enough information from the video, the request to take a specific action can be set to appear.

• A "client-side" shortcode allows the marking of content to appear or disappear after a given time interval; a "fade" effect is included. This functionality is intended to be used for special effects only, as content marked in this manner is still visible in the HTML source and, therefore, not a secure method of hiding content.
• A "server-side" shortcode allows the marking of content to be visible only during a specified date/time interval. This functionality can be used as a secure method of hiding content, because the marked content will be included in the Page/Post only when viewed in the specified date/time interval.

A TinyMCE button is included to help users build the shortcodes.

For more documentation, visit the plugin's page.