Item scheduling is a special facility in sharepoint 2010 which help to publish a document for a specified period in a publishing site.
Item scheduling can be implemented only on libraries. Versioning need to be set for the library for this.Publishing server feature need to be activated for this
Create a new content type derived from the document content type, while creating this content type add the Scheduling start date, and Scheduling end date SharePoint inbuilt custom column in the content type along with the other columns required.
Use the custom content type in the library.
Once published the document will be in the schedule.