I think Lua started catching on outside of PUC-Rio before 5.0 in 2003. Remember, LucasArts used it in Grim Fandango, and that became widely known in the game industry in 1999 or 2000. My own first exposure to Lua was in a Linux distro package repository sometime in 2000. That's why, when I was looking for a lightweight scripting language implementation in late 2004, I remembered Lua. So yes, my actual first exposure to the Lua language was Lua 5.0, but I consider myself a relatively late adopter.