Mercer,
I'm not sure what you were referencing about godstimeline.com.  I have no affiliation with it.  I don't believe we are in the Great Tribulation either.  I believe it is a period of plus or minus 3.5 years.
 
Regarding the 'falling away', it isn't an ambiguous event.  1st Timothy 4:1-3 describes the departure from faith in the latter times.  It will be marked by a so-called 'Christian' group who abolishes marriage as we know it (husband and wife) and institutes veganism (no meat).  Their false teaching will be by grand stage productions (speaking lies in hypokrisy). They will not respect the right and wrong that the basic human conscience knows, the branding (outward appearance) of their sins will be evident, but they won't care.  They will give heed to wandering spirits (demons) and doctrines of devils.
 
Megachurches embracing homosexuality, same-sex marriage, liberal theology, welcoming other world religions such as Islam, Buddhism, etc. (which are of course satanic), embracing universalism, denying hell and eventually instituting strict veganism (which is being pushed now by many).  Sound vaguely familiar?
 
In Christ,
Kevin Heckle