I’m in Australia, it’s been four months since ads started rolling out on Quora. I’ve seen an ad once in all that time.
EDIT: in the two weeks since, I’ve seen ads twice; both, inexplicably, inviting me to follow Quora on Facebook.
EDIT 2: It’s now September 18. In the 5 weeks since the last edit, I’m seeing them a lot more, maybe three or four times a day. Some of them well pitched, some of them less so; the well pitched ones, unsurprisingly, were in IT.