Force binding for WPF Text property to be UpdateSourceTrigger.Explicit

I am trying to create a control that I want to control the update of the binding using the UpdateTarget method of the BindingExpression. When in the BeginInit for the control, the binding comes back null, but in the EndInit the binding has been set but it is too late to update the binding. I get the following error: "Binding cannot be changed after it has been used." the following is the code I use to get the binding and then force the UpdateSourceTrigger to be Explicit:
 

  var binding = BindingOperations.GetBinding(this, TextProperty);
  if (binding != null)
    binding.UpdateSourceTrigger = UpdateSourceTrigger.Explicit;