Yep, millennial teenagers in my area were all over LiveJournal/Myspace/Xanga in the early aughts. And if one considers messengers like ICQ/AIM (or even IRC) as

Yep, millennial teenagers in my area were all over LiveJournal/Myspace/Xanga in the early aughts. And if one considers messengers like ICQ/AIM (or even IRC) as a form of social media then teenagers were commonly (in my area) using social media in the late 90s.