According to the list maintained by the Administrative Office of the U.S. Courts, Eleventh Circuit chief judge Edward E. Carnes has announced that he will take senior status at some as-yet-undefined date. Carnes’s tenure as chief judge ends, as I understand it, next June 3—the date on which he turns 70—so it’s reasonable to expect that that’s the date on which he will take senior status (though he could do so sooner).
In the meantime, the White House can go ahead and nominate Carnes’s successor, and the Senate can confirm the nomination. Only the post-confirmation act of appointment by the president requires that Carnes first have taken senior status (so that a vacancy exists).
Once the pending nominees Barbara Lagoa and Robert Luck are confirmed and appointed, the Eleventh Circuit will have seven appointees of Republican presidents versus five appointees of Democratic presidents. (Technically, that tally will be achieved when Lagoa is appointed, as Luck is replacing a Republican appointee.) At the outset of the Trump administration, the Eleventh Circuit had eight Democratic appointees, only three Republican appointees, and one vacancy.
Further, if President Trump appoints Carnes’s successor as well as Lagoa and Luck, he will have appointed six judges to the Eleventh Circuit. That is half of its total—higher than for any other court.
In sum, there is a strong argument that the Eleventh Circuit is the federal appellate court that will have been most transformed by Trump by the end of 2020.