Most of my premium themes include a default content XML file in the theme package. (usually demo.xml)

You need to use WordPress Importer plugin to upload the demo.xml file. If you have installed default pages on theme installation (if your theme includes this feature), delete all pages and empty the trash to avoid duplicated pages

  1. Install WordPress importer
  2. Go in the “Tools” -> “Import” section of your WordPress admin panel
  3. Choose WordPress
  4. Upload the demo.xml file included in the theme package

WordPress importer is not 100% reliable especially if you choose to download attachment images.