I posted an ad to the Community Promotion Ads - 2019 thread, and the ad has had the requisite 6 votes for several days, but as far as I can tell it has not yet run on the Q&A site. Just wanted to check to see how the timing works, or whether there's something else I need to do to trigger the ad to run. Thanks!
https://stats.meta.stackexchange.com/ads/display/5551 it seems to be already active, it just gets no clicks.
Well.... one now, since I just clicked on it. Now it says 0.07 clicks per day. So that means it was online 14 or 15 days ago (today is May 2th). That is about 1 or 2 days after you posted the add.
Beyond that, I have no idea if, how often and where those ads are shown. I have never seen them.