I was a +pack-a-day smoker from <1996-2016.
Last "daily cigarette" = around spring 2016.
I switched cold-turkey and super easily, instantly and in 1 day, because I was so amazed by the vape. I never even wanted to quit smoking, because I was so hooked. I was even a little closed-minded of vaping.
When I switched, I even tested myself with the hardest tests (that really makes you want a cig) - "morning coffee" and "weekend night beers" the first days after switching, with using only vape... and it worked super easily and I did not want a cig at all. The vape was more than satisfactory.
I also measured my resting-heart-rate too, before and after the switch. I went from 70-75bpm to 50-55bpm within 2-3 weeks. A surprisingly vast difference. 50-55bpm is similar to an athlete from what I've read.
Last "occasional cigarette" (a super seldom/rare single stick) = 2018 iirc.
When I travel internationally (once every year or two), I celebrate by having 1 or 2 cigs at a club or while drinking at night, maybe just 1-2x per week while traveling (ie: 2-5 sticks per week... far far much less than a "pack a day"). These are usually bummed or shared from someone I meet during travels, and I never buy my own pack. I only smoke them to try it out, socialize, conversation, curiosity, etc.. I do not crave it at all, after I have 1 stick.