RadAutoCompleteBox exposes the FilterStartThreshold property that defines minimum number of characters
in the input string before a filtering operation is performed. This property is useful in scenarios with web services and large data where you would like to limit
the filtering queries as much as possible. For example, require a minimum number of characters typed into a control before filter execution.
Using the FilterStartThreshold Property
The FilterStartThreshold property is of type int and can be used to define the length of the input string after which the
filtering procedure is started.
The following XAML code snippet demonstrates setting the FilterStartThreshold property (filtering will start on typing the 4th symbol):