I'd go with 3 first languages simultaneously, in 3 tracks, PL focused on programming concepts and constructs, OS focused on low-level interfaces, and SE focused

I'd go with 3 first languages simultaneously, in 3 tracks, PL focused on programming concepts and constructs, OS focused on low-level interfaces, and SE focused on what the job market requires. From first to last in each track... PL: Python, Prolog, Clojure, Haskell/Parsec OS: C, assembler, Bash, regex/sed/awk SE: Java, Javascript, HTML/CSS, Django