As you know, a sect of end timers believes the end is coming on May 21, but if you look at their "book" you'll see that they actually give themselves 5 months for something to happen.
"8. In the year 2011, what is the last day of the feast of tabernacles (feast
of the Bible)? We have learned that it occurs on October 21, 2011. Thus, there
are five months, consisting of 153 days of our calendar, during which time the
events of Mark 13:24-27 must take place. Indeed, immediately, we are
encouraged that we probably have arrived at a correct understanding of the
unfolding of the events that lead to the end of the world. In Revelation 9, God
speaks of a period of five months that identifies with the time when the sun is
darkened and judgment has begun. And 153 days, May 21 to October 21, are
exactly five months."
http://www.familyradio.com/PDFS/waat.pdfThat's right. Five more months for them to milk suckers for all they got after nothing happens on May 21.