How long does it take to become Supreme court judge from associate justice?
Do you mean how long to become Chief Justice? There’s no time limit on that. John Roberts became Chief Justice when he became a Supreme Court Justice. He had not been an associate justice prior to that time.
You don’t have to serve as an Associate Justice to become the Chief Justice. The Court has one chief justice and eight associate justices.
When there is a vacancy for the chief justice position, the president usually nominates a judge (or other individual) from the outside with proven leadership skills (Warren Burger, Earl Warren as examples). Occasionally, however, a president will elevate an existing associate justice to become the chief justice (Reagan w/ Rehnquist).