I have one kiddo, so this is very much n=1, but I feel strongly that "talking about drugs" or sex, or whatever, should be a constant conversation.
Meaning, when our son was a baby and pointing at bananas in the grocery store, we talked about how different foods make your body feel different ways. We let him pick out his own groceries (hilarious exercise in recipe creation, but fascinating because he never went for the eye level crap but picked out stuff like eggplant, fish, yogurt). We talked about how sugar makes your body feel, and he could identify it made him feel like "bees buzzing in his body!" We talked about how he had to wait to drink coffee because it made us feel like our bodies were buzzing. We talked about how sugar and caffeine are "drugs" because they are substances we can ingest that make us feel "more" of a certain way than other foods. We talked about wine and how mom didn't make a good choice and had a really bad headache ;)
The conversation was never a "thing", it was just part of explaining the world like all the other things we blabbed about, with the goal of helping our kid become a critical thinker while staying true to himself. We took the same approach with bodies, sex, money, and consumerism, and politics. We answered his questions about any topic honestly, always. Both our families have mental illness and a lot of alcoholism, and we answered questions about those things as well.
At 20, our son now has regular budget meetings with his live in girlfriend (they've been together since they were 14). He has an occasional beer or glass of wine (they've just started exploring the world of local microbrews) but neither of them has gotten drunk; the sensation doesn't appeal to them. They caucused in local elections starting at age 17. They enjoy video games, and bike rides, and late night conversations about the state of the world.
For me, it's not just about making good decisions about drugs. It's about making all the daily decisions that lead to the life you want, and that influence starts the day your kids arrive in this world. How that looks is of course different for all of our families and the mix of personalities within - we were very lucky that as parents we agreed on pretty much everything, even after divorce, and we were also very lucky that our kiddo's personality was a good fit for our parenting styles. I also recognize that just one shift in his life could lead to very different choices; I know both friends and family who became addicts in their 20s.
That's to say, I don't mean any of this as a criticism of parenting (we ALL are doing our best), but as a way of maybe tweaking the point of view a tiny bit from how our culture has typically thought about the Big Topics <3