Just received my founder's edition bundle today but no invite code. Based on the other posts it's a widespread issue that is supposedly fixed. Tried reaching out to stadia support but looks like the chat option (which is available 24 hours) has been disabled and the phone support requests are going unanswered.
@spyke01 You can keep trying support but from a lot of posts I've seen on here and Reddit, Stadia support are saying it may take 3-5 business days and to contact them if you still haven't received the code by the end of the week.
@spyke01 I think it might depend on your country but these are the options I see here in the UK...
you can also contact every other Google Support, e.g. Play, Google One or another one and ask for a transfer to Stadia.
Just have in mind: If you have any questions regarding your order, even the Stadia Team would transfer you to Hardware Order Management Team, so it might worth to contact them directly. Happened to me as well, so don't make the same mistake!
Wanted to provide an update here. I called the chromecast line and signed up to get a call back after 7 minutes. After that they were able to redirect me to the stadia support line, from there I waited on hold for 1 hour 23 minutes to be able to get on a list to be called back 3 hours later. Spoke with a rep at that point who was friendly but couldn't help. Their phone lines are backed up with calls about the codes but apparently the reps have no access to the codes. He said he was affected by it to and the best he could do was call me back on his off day tomorrow and see if I had gotten my code. If I don't get it today he said he can escalate it and they may be able to help.
He was able to confirm that the codes are going out in order based on the order date. The stadia subreddit has people posting when they get in and their order date so we may be able to use that to keep up with where the code delivery is at.
Final update here, I just got my invite code and got in. Here are my details to help others with their timeframes
Order Date: July 15, 2019, 09:30 PM CST
Invite Code Received Date: Nov 21, 2019, 11:32 AM CST