For many apps, on the first launch, it will show a screen welcoming the user or introducing the app's features. If this is not the first run, the just go straight to the main screen.

Do we create 2 div with data-role="page", for example "main" and "welcome"? Then use $.mobile.navigate(page_id) to direct to the right page?

Where would be the appropriate place to insert the JavaScript codes to check and direct to the right screen page automatically? By default, jQM will jump to the first data-role page div it can find in the HTML.