How to select a DataGrid as default loaded with a TabControl in WPF Window?

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C#

WPF

C#4.0

DataGrid

C#5.0

First of all I wanted to upload a picture that shows my way how to indicated number of lines from database files as visualization, but I haven't got a rate to upload pictures yet. Anyway.. So My matter comes from not to specify a default DataGrid in three of them with a TabControl. Because I populate a label that indicates how many record in the database with an exact DataGrid. They are three and each one have a meaning to indicate as particularly. This approach works well but only matter is first DataGrid has let's say 5 records and the last DataGrid has let's say 10 records then when the window Loaded the Label says there are 10 records in the database that belongs to the last DataGrid loaded event. I want to change this flow. Because the Window shows right UI order with tabControl's sequel. First TabControl's item shows first DataGrid and its indicator counter must shows 5 in this case. I think above explanation enough to clarify my case. Otherwise I can only show three DataGrid Loaded events and their XAML proprties.

Below is one of TabItem's DataGrid:

<TabItem x:Name="in_Progress" Header="In Progress">
            <Grid removed="#FFE5E5E5" Margin="0,0,-8,0">
                <Grid>
                    <Grid.ContextMenu>
                        <ContextMenu>
                            <MenuItem Header="Send the word into Learned" Click="MenuItem_InProgress_Click"></MenuItem>
                        </ContextMenu>
                    </Grid.ContextMenu>
                    <DataGrid x:Name="DGWProgress" 
                              ItemsSource="{Binding}"  
                              Margin="0,0,10,0"
                              CanUserAddRows="False"
                              CanUserDeleteRows="False"
                              CanUserResizeRows="False"
                              Loaded="DGWProgress_Loaded"
                              IsReadOnly="True"
                              SelectionUnit="FullRow"
                              AlternatingRowremoved="LightBlue" 
                              AlternationCount="2" 
                              Grid.ColumnSpan="2"/>
                </Grid>
            </Grid>
        </TabItem>