Agent Devine has some great advice about sex offenders and how to deal with them. I'd recommend watching more of his videos for help. He covers every topic I could think about that has to do with sex offenders.
The earlier the better!! Kids are creating online profiles for games at such a young age these days. They need to know what information it is and isn't safe to share online in the public. What's important is that children understand the consequences of oversharing so that they don't accidentaly do it or think they can get away with it.