CJ Roberts was appointed to the United States Court of Appeals for the District of Columbia Circuit in 2003. President George W. Bush nominated him as Chief Justice of the United States, and he took his seat September 29, 2005. - 26 months.
Thomas. March 12, 1990 – October 23, 1991. 19 months.
Kagan. 0 months. Between 2003 and 2009, she served as the Dean of Harvard Law School. But, she clerked for Judge Abner Mikva of the U.S. Court of Appeals for the D.C. Circuit from 1986-1987 and for Justice Thurgood Marshall of the U.S. Supreme Court during the 1987 Term.
Barrett. 35 months. She was also a law professor and clerked for Laurence Silberman of the U.S. Court of Appeals for the D.C. Circuit from 1997 to 1998, and then for justice Antonin Scalia of the U.S. Supreme Court from 1998 to 1999.
Gorsuch, 10 years August 8, 2006 – April 9, 2017. He also clerked for Judge David B. Sentelle of the United States Court of Appeals for the D.C. Circuit from 1991 to 1992, and Justices Byron White and Anthony Kennedy from 1993 to 1994.
Kavanaugh, 12 years, May 30, 2006 – October 6, 2018. He also clerked twice for the Court of Appeals and for Justice Kennedy 1993 to 1994.
Sotomayor, District Court, August 12, 1992 – October 7, 1998 (8 years); Court of Appeals, October 7, 1998 – August 6, 2009 (11 years)
Jackson, District Court, March 26, 2013 – June 17, 2021 (8 years); Court of Appeals, June 17, 2021 to present. She also served on the Sentencing Commission February 12, 2010 – December 2014 (As did Justice Breyer), and served as a law clerk to Judge Patti B. Saris of the U.S. District Court for the District of Massachusetts from 1996 to 1997, then to Judge Bruce M. Selya of the U.S. Court of Appeals for the First Circuit from 1997 to 1998, then clerked for Justice Stephen Breyer of the U.S. Supreme Court from 1999 to 2000.