First time when I actually tried? About 3 months, then was making more than I imagined, especially when I was landscaping for $8/hour prior to that. Lasted 5 years.
Second time? We'll see.
Second time? We'll see.

“There are three types of people in this world: those who make things happen, those who watch things happen and those who say, ‘what happened?’”~ Sam @ Neverblue
the key to my success has been purchasing ebooks, buying webinars, paying for people to video chat with me about their traffic sources, traffic programs, shareware, and of course the DPM forums!!! all of this has enabled me to generate over $100 (yes you've read it right, ONE HUNDRED DOLLARS) per week!
I never payed for a single e-book, webinar, training etc and I still was able top generate a significant income. I think you're better off finding out what works on your own (think trial/error) instead of blowing a bunch of money on stuff that probably isn't going to help in the long run.
you seriously didn't realize he was trolling? i dont even know what a "webinar" is but it sounds fuckin stupid
"You're born, you take shit. You get out in the world, you take more shit. You climb a little higher, you take less shit. Till one day you're up in the rarefied atmosphere and you've forgotten what shit even looks like. Welcome to the layer cake son."
^ just because it sounds cool and it's from a movie. Truth is that some people are just better at making money online and reach the million mark before they turn 16. Others, like the OP, might fail for decades and just begin to break even at 61.