I personally think that there is not a “too young” age for social media. Since social media is becoming so ubiquitous in everyone’s daily life, it is just another tool to communicate on multiple levels.

The most important thing is to secure your virtual identity from the get-go at any age. For children especially, privacy is very important insofar as the contact information, posted pictures and anything else that may expose personal information.

Like anything else, the key is understanding the implications and ramifications that may follow anything that may be posted.

As far as securing unique user names, http://www.NameChk.com can help in that process.