While we specifically documented that you should not depend on
the value being correct in onCompleted for 5.3, it is not
optimal that the initial value is consistently set to 0 and later
changed to it's appropriate value. This patch ensures that delegates
are not instantiated until after the model model and row values
have been fully initialized.

Task-number: QTBUG-38307
Change-Id: Ib3300539a0283c997ab8b808fb229d3f22ed6324
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>