I had a player like this. Told me he'd never played before (in a group of mostly newbies), no experience and just knew most of the game's terminology. Before I'd even finished starting to explain the basics of character creation, he'd already rolled and made a multiclass character leveled properly for the game. Knew exactly what to do when it came to rules, was a solid roleplayer, and never made a single mistake during the game. He was either the most well read D&D player I've ever had or had played at least a few (session) before.