Its good to see an estimate time line, gives us guys looking for our first dollar a little something to look forward too.
For me it took less than a month. But it was primarily because my website was quite popular and I was using another ad network making $400-$500 using that network.
It all depends on what type and quality of the website you have (certain sites get better paying ads etc...) and how much effort you put towards promoting it. It took six months to get my first $100 with a software site, others have made the same amount in much shorter periods of time. It's all about quality, type and effort.