First week for me. Still do from time to time.
I had much the same experience myself, my cough was just about gone after two weeks, and I smoked 1 to 3 packs a day for 30 years. Everyone's different.My problem was coughing up phlegm when I was smoking. One pack or more smoker for over 30 years. Nearly coughed up a lung every morning for 10 years, at which my children asked me was I alright because the coughing was so intense and uncontrollable.
Once I began vaping exclusively, the coughing spells nearly disappeared.
I smoked for 55 years...a pack and then some. I always had a smokers cough! The last few years that I smoked I had this constant tickle in my bronchial tubes that would make me cough....especially when I laid down in bed to sleep. Sometimes I would also wake up in the middle of the night coughing. After one week of vaping my husband said "do you realize that you are not coughing anymore?" haha as if I had not noticed! I did not cough at all when I was first vaping like so many do when they are trying it for the first time. I have been cigarette free for 2 1/2 years!!! If I had known about vaping I would have stopped smoking earlier. I hated what cigarettes did to me!!! It was like a ball and chain around my neck that I could not shake.
Curious how long it took some of you to start coughing up all the brutal stuff in your lungs from years of smoking. I've only been completely off the smokes for 10 days now so nothing for me yet haha