I am trying to load data using datatable, but when I try to pull bulk data like more than 25k that time it should show loading image or any text like "Please wait .. ".  

Javascript

  $(document).ready(function () {
      $(function () {
          $('[id*=gv_order]').prepend($("<thead></thead>").append($(this).find("tr:first"))).DataTable({
              "responsive": true,
              "sPaginationType": "full_numbers",
              "ordering": true
          });
      });
  });

 GridView

                              <asp:GridView ID="gv_order" runat="server" AutoGenerateColumns="false"   CssClass="table table-bordered table-striped display" DataKeyNames="t_orno" Width="100%">
                                  <Columns>
                                      <asp:TemplateField HeaderText="#" HeaderStyle-HorizontalAlign="Left">
                                          <ItemTemplate>
                                              <asp:Label Text='<%# Container.DataItemIndex + 1 %>' runat="server" />
                                          </ItemTemplate>
                                      </asp:TemplateField>
                                      <asp:BoundField DataField="t_orno" HeaderText="Order No"  />
                                      <asp:BoundField DataField="t_odat" HeaderText="Creation Date" DataFormatString="{0:dd-MM-yyyy}"  />
                                      <asp:BoundField DataField="t_ddat" HeaderText="Delivery Date" DataFormatString="{0:dd-MM-yyyy}"  />
                                      <asp:BoundField DataField="t_termop" HeaderText="Terms of Payment"  />
                                      <asp:BoundField DataField="t_suno" HeaderText="Supplier Code"  />                                   
                                  </Columns>
                              </asp:GridView>

 Code Behind

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
        If Not IsPostBack Then
            Me.BindGrid()
        End If
    End Sub
    Private Sub BindGrid()
        dbconn.OpenConnection()
        Dim query As String
		query = "sp_t_getPOSummary"
        Dim cmd As SqlCommand = New SqlCommand(query)
        Dim sda As SqlDataAdapter = New SqlDataAdapter()
        cmd.Connection = dbconn.con
        sda.SelectCommand = cmd
        Dim ds = New DataSet
        sda.Fill(ds)
        Dim dt = ds.Tables(0)
        If dt.Rows.Count = 0 Then
        '  lblreqnerror.Visible = True
        Else
            gv_purchase_order.DataSource = ds
            gv_purchase_order.DataBind()
        End If
        dbconn.CloseConnection()
    End Sub

I tried putting below code but no luck 

<asp:UpdateProgress ID="UpdateProgress1" runat="Server" AssociatedUpdatePanelID="UpdatePanel1" DisplayAfter="1">
    <ProgressTemplate >
        <asp:Label ID="lblwait" runat="server" Text="Please wait.."></asp:Label>
    </ProgressTemplate>
</asp:UpdateProgress>