That's true! Joining your first sports team (or of course getting your first stitches). That presents the interesting question of what is the right age for a child or young adult to begin encountering this checklist and this conversation on their own. You're right that it would be best done 'incrementally' rather than only at the Big Steps.
Your comment has got me thinking how the questions and discussions would change as people age. What are the unknowns that seem scariest at the different stages of our lives, and what questions get people thining about them? That would be worth researching.
That's exactly right: it's important to get people thinking about these issues at that crucial time in their lives when they start to think about the book-ends of a life cycle.
I would use the focus group to find the most productive set of questions to include on a checklist. The next steps would be to come up with a well-designed, simple and eye-catching prototype. After that, I would tackle the question of how to get this checklist into the appropriate spaces. That would require some good communication and perseverance, I imagine.