I had to transition or dual/use for awhile, it was pretty tough after 30 years of smoking. About a month after going all vaping I wasn't coughing my brains out every morning, and it was a slow improvement after that, eventually could breathe a lot better, plus not reeking was really nice. My sense of smell and taste took a long time to come back, but as I said I was a heavy smoker for tons of years. At first I had to have pretty strong juice and higher nic, this slowly changed. New vapers seem to need higher nic to satisfy the cravings. Depends on how much you smoked. If you listen to some of the young dudes at the vape shop who might have only smoked half a pack for one or two years they might act shocked if you want something stronger than 6mg. You will find your own level. When I first started I needed 16 or 18mg juice...but a few toots of that and I was good to go for a half hour. I slowly weened down, now I generally vape 9mg in either tanks or drippers, anything less and I'm chain vaping. I use 12mg at work when I can't run outside very often. If you are wanting higher nic juice you're going to have to search the web....not as plentiful as it used to be but you can still find it...most shops only carry 3 or 6 mg these days.