I ordered mine on the 7th and it just arrived today and still have not received an invite code.
Chat support does not work and I don't dare attempt to call.
I too took the day off yesterday and with such a let down not sure if these first impressions will be altered which is sad.
If you've already receivedr the bundle, there isn't anything you can do unfortunately but wait for the code to arrive. You can contact support via https://support.google.com/stadia but they will likely tell you it may take 3-5 business days and to contact them again if you still haven't received the code by the end of the week.