How can I defer loading UpdatePanel content until after the page renders?

Question

Old hand at ASP.NET, new to the UpdatePanel. I have a reporting page which executes a fairly length SQL query... takes about 10 seconds right now. What I would like to do

Answer 1

Updating this with my solution, I pieced together mostly from the first answer above.

I need my page to load, then then start loading content for my update panel. The panel calls some webservices and we don't want the whole page to crash in the event that the remote server doesn't respond. We don't want the wait either.

My HTML:

My Code behind snippets:
In page_load:

ScriptManager.RegisterStartupScript(Me.Page, Me.Page.GetType, "LoadUpdate", GetPostBackEventReference(hiddenAsyncTrigger, String.Empty), True)

And the button handler:

Sub LoadUpdatePanels(ByVal o As Object, ByVal e As EventArgs) Handles hiddenAsyncTrigger.Click
        System.Threading.Thread.Sleep(5000)  'wait 5 seconds so I can see the page change
        imgSpinner.Visible = False
        lblWait.Text = "Content is now loaded."
        'udpCheckout.Update()
    End Sub

This was my test to see if I could get it working. Now to replace all of this with the real code!