Arnold Schoenberg started composing at 16 years old after his father died.

When he started composing

www.bach-cantatas.com/Lib/Schoenberg-Arnold.htm

The musical period he was in is Romantic.

He started composing in 1891

http://www.telegraph.co.uk/culture/music/classical-music-guide/10254199/Ivan-Hewetts-Classic-50-No-35-Schoenberg-Farben-from-Five-Orchestral
-Pieces.html