I made an income from my hubs from day two. But not from any ads. I wrote my article to drive traffic for a products that I promote and sell.
It has never stopped earning me money thought at times it does slow down.
I think this is mainly because I have not had much control over my order page.
I am changing that right now. I hope to be done before Friday.
At the present I am only promoting 2 products on Hubpages and they both are performing well. I think this is the best way for me to use Hubpages rank and so far I have let them keep any and all of the ad revenue. If there is any.