The Ads Won't Start Flowing Immediately

After you secure relationships with ad networks and they send you their ad tags (the bit of code that you need to add to your site or ad server to make the ads flow in), don't be surprised if it takes awhile for the ads to start showing up, or if they seem to be running slowly at first, or if they generate revenue at a rate below what you requested. It can sometimes take between two and four weeks before the ad exchanges get settled and push the right ads, in the right amounts, in the direction of your site.

(MLA 8th Edition)