I first tried E-Cigs a few years ago.. They didn't do much for me, I spent several hundred dollars, and never really went more than a day or two without smoking a real cigarette. I wrote them off as a gimmick.
I really didn't give them a second thought until a few months ago when a friend of mine switched to E-cigs. He's currently using a generic Blu-type setup, and it's working fine for him. I started seeing commercials on TV about E-cigs and thought I'd look back into it. After a week or so of research, I decided to try something I considered a step up from the Blu style setup. It was okay, but I'm not a real big fan of the cartomizers. I mostly ended up flooding them. Not to mention, the process of refiling a cart is a pain, as I tend to burn through them rather quickly.
I realized after about a week I wasn't going to be able to keep doing this. It was easier (for me anyway) to just go buy a pack of cigarettes and smoke those. Time for more research.
I found the eGo type e-cigs. Much easier to refill, and about a zillion vendors sell them. Now I'm getting somewhere, I think to myself as I smoke one of my last real cigarettes.
I also found this forum. I read it endlessly. Soon realized that most everyone's tastebuds suck!! and there is no e-liquid that tastes exactly like my beloved Marlboro Lights, no matter what anyone says. Halo isnt' as good as most people would lead you to believe and Johnson Creek isn't as bad, and no matter how hard you try, you will probably never know what Radiator Pluid tastes like because it's always sold out.
I did, however, discover rebuildable atomizers, batteries that last a whole day or more, and things I never knew I needed like Kanthal wire and SS mesh or SS wire rope, or aquarium airstones.
What I needed, as much as I needed to quit smoknig, was something to keep my mind off that fact that I wasn't smoking. Wrapping wire around metal wicks and doing it again, and again and again, kept my mind off the not smoking part. Looking at this or that vendor's website also kept me busy... and broke.
A few more weeks into this, I'd discovered some e-liquids that I actually liked! Some even (sort-of) remind me of smoking.
Then, while washing the car and cleaning out the inside after a long winter, I found a half of a pack of cigarettes under the seat. I toyed around with the idea of trashing them, but of not before I took one out of the pack and smoked it.
Then I smoked another one, then another, then another. I didn't enjoy it (though I kind of wanted to. Hard to give up 30+ year old habits). I really got nothing from those cigarettes that my newly discovered e-liquids wasn't giving me from the VAMO and AGA T+ I'm currently using.
So to answer the question... It took me about two weeks to quit smoking after I started vaping, a few more to decide I wasn't going back. Ever.