We have a book called Everyone's Got A Bottom that I would reccommend for any house. The boys enjoy it (although Imran mainly likes spotting the cat on each page lol) and it introduces self-protective strategies and the correct names etc in a really non-threatening way.

Yasin is 3 and he likes this book.

I think that you can use the correct names from birth. If you've been using other names you can just switch over any time.