When is the first BFR/Starship Mars flight?

“…that's our goal is to try to make the 2020 to Mars rendezvous the Earth Mars synchronization happens roughly every two years so every two years there's an opportunity for just to fly to Mars so then in 2024 we want to try to fly for ships two of which would be crude…”

— Elon Musk, 29 September 2017 · Watch: IAC 2017 — Making Life Multiplanetary · 38:08 ↗