Address confirmation

I finally got partnered some weeks ago. Still about 120 subs to go for the full deal.

I set up the AdSense and filled the tax form (hopefully the right one). It tells me that the next step is address confirmation but I don't find anything where to do that.

Is that after full monetisation or am I missing something?

I'd like to do that as early as possible because of lousy postal service in my country...