I'm going to throw this here as it's a pretty noobish question, as I haven't worked with AdSense in close to a decade. How long does it typically take to get approved on the second step, once you've added the code to your site and are showing blank white space?
"Your application for x is under review. You'll only see blank ads until your account has been fully approved."
"Your application for x is under review. You'll only see blank ads until your account has been fully approved."