It depends firstly whether manslaughter is 'on the table'.
I believe in Victoria, that a majority verdict is possible in a manslaughter case - so, 11 jurors only need to agree on manslaughter after a minimum of 6 hours of deliberation.
They either need 12 for murder, or 11 for manslaughter if that is an option allowed - which I don't think we will know until the judge instructs the jury before deliberations. IMO
This practice is governed by the Juries Act 2000 (Vic), which outlines the conditions under which majority verdicts are permissible in criminal trials.
Procedure When Unanimity Isn't Achieved (Manslaughter)
Initial Deliberation: The jury attempts to reach a unanimous verdict.
Judge's Direction: If unanimity isn't achieved after six hours, the judge may direct the jury that a majority verdict is acceptable.
Outcome:
Majority Verdict Reached: The verdict is accepted and recorded.
No Majority Verdict: If the jury cannot reach a majority verdict, the judge may declare a hung jury, leading to the possibility of a retrial.
Manslaughter Trials: Majority verdicts (11–1) are allowed after six hours of deliberation.
*Not a lawyer.
en.wikipedia.org