All PC players globally will get access to HITMAN at the exact same time.
To make for a smooth launch, we're making the game available during Valve office hours, giving us a global unlock time of 09:01 PST on March 11.
In other timezones, that equates to 17:01 GMT on March 11 and 04:01 AEDT on 12th March.
Full details are here: https://hitman.com/news/hitman-global-launch-times