I have believed that the Great Tribulation begins with some sort of nuclear attack on the United States.
Events are emerging which increase the probability of such an event.
The archrivals at the end scene are the US and Russia.
Russia is in a dire state. Its economy hangs by a thread. It's political influence has been reduced to its aging nuclear arsenal. Russia experienced a financial collapse in 1998 when oil was around $12 per barrel. It has been averaging between $24 and $28 per barrel for the last couple of years. This windfall has kept Russia's economy afloat.
Russia is affraid of the drop in oil prices that will occur after an Iraq invasion. Iraq will ramp up its production to rebuild its economy. The US will preside over the Iraq oil industry after the war. The US needs cheap energy to keep from suffering the sort of stagflation Japan has been dealing with for the last 10 years.
Russia needs to derail the US attack on Iraq. How is it going to do this? Simple. Detonate a nuclear weapon in Manhattan. Even if the device is identified as a Russian nuclear weapon the Russians can avoid responsibility by claiming it must have been stolen from their stock. The terrorist who explode the device might really believe that they bought the weapon on the black market. Of course the Russians would have no problem delivering a nuclear bomb via "mafia" connections.
This would probably happen at the point where the United States appears to be ready to attack Iraq. This kind of a blow would sap all will to conduct an expensive war against Iraq. New York City would have to be salvaged not just a couple high-rise office buildings. This would be a repudiation of Bush's pre-emptive strategy because his actions will appear to have caused the very thing he wanted to avoid. It is a rare opportunity for Russia to deal a serious blow to the USA and level the playing field a little bit.
Many on this board will be sad for New York but glad to see Watchtower HQ destroyed. But it will be a sign to true Christians to flee "Babylon the Great/Rich USA". Jehovah's Witnesses will still have their world-wide brother hood. There are enough JW's in Latin American lands to accommodate the 1,000,000+ witnesses who would be moving in.
After a period of time (3 1/2 years?) the United States will figure out the Moscow/Bomb connection. Russia will finish off the USA before it can retaliate. This could lead to a sun darkening cloud of smoke and dust that will create great hardship in the Northern Hemisphere.
There is more to this but this is enough at this point. Of course I have a scriptural basis for all my assumptions.
Expected date of Great Tribulation? Late December. Within a week before Christmas.