Redirect client 5 seconds after CreateUserWizard created the user

After a user has finished registration, i want to show an info message and redirect the user to the site's main page after 5 seconds. I can do a delayed redirect easily:
function delayedRedirect(){
setTimeout('document.location=\'default.aspx\'', 10000);
}
I'm wrapping the CreateUserWizard in an UpdatePanel.
How can i call this method only when the user was succesfully created?

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