I started on a $20 pen style device and my daily cigs declined 80% the first day and mostly stayed there. A week later I got an N mini and spinner battery, still smoking 4 cigarettes a day.
My start was rocky. I was having lots of peculiar withdrawal symptoms. The liquids made me slightly queasy for the first three weeks. The nic level I thought I needed gyrated up and down. After six weeks of learning to vap I let my cigs run out. That day I bought an Atlantis with IPV 2s mod. I've settled on a 12.mg 50/50 coffee flavor. I rotate the Atlantis, N mini and an Egrip with RBA. I haven't bought more cigs in the couple of months since.
I gave a brother who still smokes an N mini, an Istick, and 30ml of my liquid on Christmas day. We stepped outside for a smoke. I smoked one of his cigarettes (and never took another) to make the point that I'm not a smoker any more. I've lost interest. There will be no relapse because I would rather vape. Get to that place, I told him, and you're home free. Before we parted on Sunday I could see he was vaping for the nic.
He reports he is is using the setup, smoking just a few cigarettes a day and excited about the prospect of becoming a non smoker. Decent equipment, the right liquid, realistsic expectations, patience, mentoring, it all helps. Vaping addresses relapsing. That's what makes it a game changer.