ember - 10:16 pm on May 15, 2013 (gmt 0)
Levo, on one site they targeted immediately, similar to Adsense. On another, it took about a month.
And I should say that occasionally I'll get an email from my account manager saying that they're trying a new color or new design for a certain ad block. I just have to go along with it, but the changes usually, although not always, improve the RPM. They have even called me out of the blue to chat about my sites, etc. They also pay on time. Their stats aren't nearly as detailed as Adsense, though, and don't even show CTR or EPC. Just pageviews, RPM and earnings per channel.
I know that they do not work for everyone, but I'm satisfied with them.