So just to clarify the overlapping generation this. It's two generations overlapping.
What is the definition of the individual generations then? The original generation changed from those who saw and could understand the events of 1914 to those who were born in 1914.
So let's be generous and say it was those born in 1914 and give them a lifespan of 80 years (1994). How much overlap should there be? Ten years? One hour? I'm going to say 4 years to keep things nice and even as the GB don't clarify what an overlap means.
So add another 80 year lifespan onto that (from 1990) and you have 2070.
So the start of the great tribulation (the cut off date for witnessing etc) will be sometime in the next 57 years. If you really wanted to extend things you could argue the lifespans are longer and add another 30 years making it 3000. But also consider there's no indication that it will be at the tail end 'it is coming as a theif in the night'. It could happen anytime between now and then.
I'm 30 now, so it's possible I might be around still in 2070 or a bit later. I may not see armageddon, but I have a pretty good chance of seeing the start of the great tribulation.
yay!