First Make backup of all Jio apps us ES File Explore or any backup app from store.
Uninstall all Jio app including My jio app from your device.
Now download MyJio v3.2.05
Now Simply turn off your internet data connection.
Install open My Jio app and other all 10 Jio apps which you have made a backup in first step.
Now open MyJio app Click on get jio sim options and now on your data connection you will get a msg like congratulations you have activate your preview offer.
btw JioFi’s not shifiting to Welcome offer , just dwnloaded 10gb