Yes.
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AnonymousWhat do you say to that?A lot of people are wrong. There is no problem with using any of those verb tenses.
AnonymousI haven't done that since...not I didn't do that since...That is different from your original. 'Since when' is a fixed phrase when fronted on a question: it is an expression of displeasure or surprise.
AnonymousWhy say since when did you you stop when you can say 'when did you stop smoking'?I have just explained that in my previous post.