I'm five months in now. Had immediate success with reducing my cigarette use, but only reducing. I was down to about half a pack of Capri menthols (light, skinny, wimpy cigs) a day, got down to 3 a day within a week. Just could not kick those last few each day. When stress hit, I craved cigs, not vape, so that would go up and down some. Started out at 11 mg liquid. Then got a bunch of 36. Still craved those last few. Different flavors helped, could change up when one got boring. Made my cigs taste like freeze dried ... hair, but I still wanted them. Until a few days ago. Eastmall's EM4 (have only used M401) for the manual control, and kicked my liquid up with some of the 60 mg mixing liquid, to somewhere around 48 mg, including some extra VG for the cloud of vapor effect that lets me know I'm vaping. Now on day 2 without a cig, finally!
I include this because I am totally an example of previous intake not matching what was needed from my e-cig for nicotine. I didn't smoke a lot, and really wimpy cigs at that, but it takes some serious juice to satisfy. Friend of mine started the same time I did, and in 3 days dropped cigs, went from 1-2 packs of whatever was cheapest daily to 36 mg liquid with no trouble, and wasn't using a lot of juice, little more than a mil a day.
End result, just keep with it. I was considering a high-end mod with more capacity, vapor, ect, but just ended up needing a whole lot of nic in a device I was otherwise happy with. I've even started using the auto batteries and filled carts again, refilled with super high nicotine juice, it works for me...