Hello! I have worked in similar project before with similar terms! I know how to get AdSense approval from Google , how to verify ownership etc. I can also help you to place those codes in proper places. Also I can help you setup tracking
You don't have to make milestone payment until the ads show up in your site. Usually takes less than 3 days, I am being cautious about time limit though .
If this sounds OK, ping me on chat!
Thanks!