Please take another look at all the sources I previously mentioned. Indeed, in the First Look demo, the busy indicator is visualized on pressing a button, but this is just to simulate data loading exactly at the time you are looking at the example. You can take a look at this demo for instance and check how its IsBusy property is bound and used.
The exact implementation depends entirely on your specific scenario.
All the best,
the Telerik team
Explore the entire Telerik portfolio by downloading the Ultimate Collection trial package. Get it now >>