(covers information from several alternate timelines)
Sunday was the first day of the Human week.
When Wesley Crusher came on board the USS Enterprise-D in 2370 and moved into his own quarters for the first time, he told his concerned mother, Doctor Beverly Crusher that he would visit her "in the old Doctor's Home every Sunday". (TNG: "Journey's End")
In an alternate timeline in 2404, Admiral Kathryn Janeway made her regular visits to Tuvok at Starfleet Medical on Sundays. When she instead paid him a visit on a Thursday, he believed her to be an impostor, due to the degenerative neurological condition affecting his judgment. (VOY: "Endgame")
|The days of the Human week|
|Sunday • Monday • Tuesday • Wednesday • Thursday • Friday • Saturday|