You can setup one website online.
After fully completing your design and content of this first website.
You can export all the posts and pages using WordPress admin -> Tools -> Export You will be prompt to install the required WordPress plugin. Follow the instructions to complete the content export. It will be in the form of a xml file.
To import this xml file into your other WordPress installations. Go to WordPress admin -> Tools -> Import You will be prompt to install the required WordPress plugin. Follow the instructions to complete the content import.
You can also export the Theme Options settings via Theme Options -> Backup -> Transfer Theme Options Data You can transfer the saved options data between different installs by copying the text inside the text box. To import data from another install, replace the data in the text box with the one from another install and click “Import Options”.
Layer Slider can also be exported and imported.
As long as you keep your first online website as demo site, you will be able to import it’s content to other newly setup site.