I think it all depends about market, niche, industry you are covering with your blog.
If you are a hardworker, if you have a very special knowledge, if you want to learn a lot and work a lot of money could arrive after a certain period of time, at least 2 years of very hard work. Your objective must be only one: Be the Best, be the most reputable in that niche that you are covering.
You can get much more with a % of products or/and services that will be sold within your Blog than with tons of ads with a low CPM.
Over again: less is more.
