Create Loading Screen while Page load in VB.net

I want to call the loading screen while the page load in vb.net.

I have my Loading screen design inside the Loading.html

I try to use this way to call the loading screen:

 Public Shared Sub ShowLoading(page As Page)
        Dim script As String = "<script>" &
                              "function showLoading() {" &
                              "$('body').append('<div id=""loading""></div>');" &
                              "$('#loading').load('/Module/Common/Loading.html');" &
                              "}" &
                              "</script>"

        ScriptManager.RegisterStartupScript(page, GetType(Page), "ShowLoadingScript", script, False)
    End Sub

vb.net code behind:

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    ShowLoading(Me)
End Sub

with this way it cannot auto call while page load, it need me to put onclientclick=”showLoading() in the button just come out the loading screen.

Does anyone can help me thanks in advance