Bill started writing music by age five after being introduced to Bill Haley & The Comets and receiving a keyboard from his parents. As a teenager he acquired a guitar and joined various metal bands. He credits Metallica as one of his earliest influences, and later saw parallels between metal and electronic music.[
His first exposure to electronic music occurred at 18 when a friend took him to a psytrance show (known as a doof) on a beach in NSW, Australia. At the time, he thought the CDJs were playing everything live and was amazed that someone could do so much complex production on the spot. His foray into electronic music production began shortly after, when his parents bought a Macintosh computer. Starting with GarageBand, Day quickly found Ableton, which he still uses today. He received a bachelor’s degree in Audio Engineering from SAE Institute, in Sydney, NSW, which helped solidify his electronic production skills. Production appealed to Bill because of the frustration of having to work around other musicians in bands, a sentiment echoed by Frank Zappa.