I'm another user who got their new paperweight and waiting on the code. This whole botched launch really sours the taste of the whole service. I was already skeptical of Stadia back when I ordered, but was curious enough, and wanted the founder's controller, to go ahead and pre-order. Now I'm starting to question my choice...
Edit: I wanted to add, I received an email from stadia giving me tips before playing stadia. So something in the system already recognized that I was receiving my founder's pack. I would've thought that if that was the case a code would have been sent too.