The yearly commemoration of 5 April 2063, when Zefram Cochrane's warp flight brought the Vulcans to Earth, celebrated aboard Voyager in the episode Homestead.
First Contact Day marks the anniversary of 5 April 2063. On that day Zefram Cochrane flew the Phoenix at warp speed and a passing Vulcan survey ship landed at Bozeman, Montana, to greet him, as shown in Star Trek: First Contact.
The holiday is seen in the Voyager episode Homestead, set in 2378. Neelix throws a party in the mess hall for the 315th anniversary, with a jukebox playing the rock and roll Cochrane loved and a table of his favourite cheese pierogi. He tries to get Tuvok to say the Vulcans' first words to humanity and to join in the dancing.
Tuvok declines. At the end of the episode, as Neelix leaves the ship for good to live among other Talaxians, Tuvok gives him a small dance step in farewell.