Bai`ram´
n. 1. Either of two Mohammedan festivals, of which one (the Lesser Bairam) is held at the close of the fast called Ramadan, and the other (the Greater Bairam) seventy days after the fast.
So I guess we have to assume they were talking about Greater Bairam, 70 days after the fast is over. Ramadan was over on 26 November, wasn't it? So that takes it sometime into the first week of Feb for Greater Bairam, but this event is supposedly to happen sometime before that.
"Bairam" referred to on this link by liz44040
9 December 2003-- A message posted on a monitored Islamic jihad forum suggests the release of yet another videotape prepared by al Qaeda and featuring Osama bin Laden. The taped message will purportedly contain a message from Osama bin Laden about a "great event that will shake the world" (terrorist attack) that will take place before the Bairam (feast 70 days from Ramadan). The taped message will reportedly be broadcast after this large scale attack.