Does "Have you ever..." usually implies that at any time before now? The time period does not continue into the present. It is also usually seen with "ever (before)" or "never (before)"? Is that right? So here i get an example for you: let's suppose that i am making a phone call to a person, and she asks me:" have you ever smoked", and i admit that i never smoked before, but how about i am smoking right now-- while i am making phone, i am smoking. So can i reply :YES ? But if the sentence "have you ever..." means at any time before the moment of speaking, then i have to say: NO?
The situation you described, where the smoker says he has not ever smoked [until right now] is called equivocating, lying in fact and in intention while trying to deceive the person you are lying to through a clever use of words. (I have four children who are all world-class equivocators.) The smoker in your story could not say he has never smoked if he smoked at any time (even one second) before saying it. He could truthfully say that he has never smoked and then (after saying it) light up his first cigarette ever.
In most contexts, the structure "have you ever done X?" naturally relates to the past.
However, it can relate to any time up to and including the present.
For instance, if you were to phone me and say, "have you ever eaten champagne truffles?", at the very moment that I was eating champagne truffles for the first time, I would not be justified in saying "no".
On the other hand, to say "yes" might be slightly misleading, as almost all our experiences lie in the past. (It's very unusual to experience something for the first time at the very moment that someone asks us about our experience of it!)
So instead of a yes/no answer, you would probably explain that you were in fact just eating champagne truffles for the very first time.