Waiting it out will do nothing, that message means that you phone is still locked (presumably to Vodafone).
Even an unactivated giffgaff SIM will display signal bars/dots and will not request a 'network PIN', 'SIM unlock code' or display a 'SIM not supported' message on an unlocked phone.
Do you get any signal bars? No signal bars is a pretty clear sign that the device is still locked to a network other than O2 / giffgaff.
Have you tried / can you please try the SIM in another (definitely unlocked) device? If it works then your device is still locked and you need to either contact Vodafone or a good mobile unlocking service.