Public ReadOnly Property TimeExtent As TimeExtent

public TimeExtent TimeExtent {get;}

<StackPanel Name="StackPanel1" Height="400" Width="400" Margin="0,0,0,0" HorizontalAlignment="Left" VerticalAlignment="Top" >
    <esri:Map Background="White" Name="Map1" Height="200" Width="400">
    
         <!-- Define an ArcGISDynamicMapServiceLayer that has TimeExtent information. -->
         <esri:ArcGISDynamicMapServiceLayer 
              Url="http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/Earthquakes/Since_1970/MapServer" />
              
    </esri:Map>
    
    <!-- TimeExtent Property (Read Only) -->
    <TextBlock Height="23" Name="TextBlock_TimeExtent" Text="{Binding ElementName=Map1, Path=Layers[0].TimeExtent}" />
</StackPanel>

private void MainPage_Loaded(object sender, System.Windows.RoutedEventArgs e)
{
     
  // Create an ArcGISDynamicServiceLayer. The Map1 object (a Map class) was previously defined in XAML.
  ArcGISDynamicMapServiceLayer myArcGISDynamicMapServiceLayer = new ArcGISDynamicMapServiceLayer();
 
     // Add an ArcGISDynamicMapServiceLayer that has a valid TimeExtent.
  myArcGISDynamicMapServiceLayer.Url = "http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/Earthquakes/Since_1970/MapServer";
  myArcGISDynamicMapServiceLayer.ID = "MyUniqueName";
  
  myArcGISDynamicMapServiceLayer.Initialized += new EventHandler<EventArgs>(ArcGISDynamicMapServiceLayer_Initialized);
  Map1.Layers.Add(myArcGISDynamicMapServiceLayer);
  
}
             	
private void ArcGISDynamicMapServiceLayer_Initialized(object sender, System.EventArgs e)
{
             	
  // The TextBlock_TimeExtent (a TextBlock object) was defined previously in the XAML.
            
  ArcGISDynamicMapServiceLayer myArcGISDynamicMapServiceLayer = (ArcGISDynamicMapServiceLayer)Map1.Layers["MyUniqueName"];
             	
  // TimeExtent Property (Read Only)
  if (myArcGISDynamicMapServiceLayer.TimeExtent != null)
  {
    TextBlock_TimeExtent.Text = myArcGISDynamicMapServiceLayer.TimeExtent.ToString(); 
  }
  else
  {
    TextBlock_TimeExtent.Text = "[NO TimeExtent SERVICE]";
  }
  
}

Private Sub MainPage_Loaded(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs) Handles Me.Loaded
             	
  ' Create an ArcGISDynamicServiceLayer. The Map1 object (a Map class) was previously defined in XAML.
  Dim myArcGISDynamicMapServiceLayer As New ESRI.ArcGIS.Client.ArcGISDynamicMapServiceLayer
 
     ' Add an ArcGISDynamicMapServiceLayer that has a valid TimeExtent.
  myArcGISDynamicMapServiceLayer.Url = "http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/Earthquakes/Since_1970/MapServer"
  myArcGISDynamicMapServiceLayer.ID = "MyUniqueName"
  
  AddHandler myArcGISDynamicMapServiceLayer.Initialized, AddressOf ArcGISDynamicMapServiceLayer_Initialized
  Map1.Layers.Add(myArcGISDynamicMapServiceLayer)
  
End Sub
             	
Private Sub ArcGISDynamicMapServiceLayer_Initialized(ByVal sender As System.Object, ByVal e As System.EventArgs)
             	
  ' The TextBlock_TimeExtent (a TextBlock object) was defined previously in the XAML.
     
  Dim myArcGISDynamicMapServiceLayer As ESRI.ArcGIS.Client.ArcGISDynamicMapServiceLayer = Map1.Layers("MyUniqueName")
             	
  'TimeExtent Property (Read Only)
  If myArcGISDynamicMapServiceLayer.TimeExtent IsNot Nothing Then
    TextBlock_TimeExtent.Text = myArcGISDynamicMapServiceLayer.TimeExtent.ToString 
  Else
    TextBlock_TimeExtent.Text = "[NO TimeExtent SERVICE]"
  End If
             	
End Sub