More specifically 21 May.
At around 6 p.m.
Their RV Caravan of Doom pulled into Washington, DC this week to spread the word about the predictions of Harold Camping, who, it seems, already predicted (in 1992) that the world would end in 1994.
A nice detail from the Washington Post article:
...by lunchtime Thursday, about 50 area residents joined up with the caravan to support his message. Among them was Gary Vollmer, who took a leave of absence from the Department of Homeland Security to spread the word. He’s supposed to go back on May 23. “But I’m not going back,” he said. “I’ll be gone on the 21st.”
Still, not all of them seem quite so certain:
Another man was so perturbed by the May 21 message that he brought over a woman he found on the street who needed money. He asked whether the Camping followers would give her some cash, because there was no need for them to keep money with the world ending. They did not.
Oh, and as to that 6 p.m. timing, don't worry about figuring it out in relation to your own time-zone, as God has worked out this apocalypse to be as convenient as possible:
The end will come sometime around 6 p.m. on May 21 — not 6 p.m. California time or New York time or Hong Kong time. The world will end at 6 p.m. only when it is 6 p.m. locally, Camping said, citing his calculations. “People will see this coming to them from around the world,” he said. “It will follow the sun around.”