What I've pieced together in the article below best sums up my thinking on a possible gap between the rapture and the start of the tribulation.
Gog Magog War Ezekiel 38 & 39
Chapter 38, verse 3 states, “I am against you, O Gog, chief prince of Meshech and Tubal.” In a short explanation, the names mentioned are sons of Japheth (Noah’s son). They are also the brothers of Magog, all who settled to the north of present day Israel. Vss 5,6 “Persia, Cush, and Put will be with them, all with shields and helmets, also Gomer with all its troops, and Beth Togarmah from the far north with all its’ troops- the many nations with you.” Cush is the upper Nile region (presumably northern Egypt ) and Put is modern day Libya. Gomer is another son of Japheth and Beth Togarmah is Gomer’s son. Historically, they are regarded to have originated north of the Black Sea . North of the Black Sea is present day Ukraine and the western most reaches of Russia. All put together, the nations described are currently Muslim nations that surround Israel from all sides.
Verse 8 proclaims that these nations will “invade a land that has recovered from war, whose people were gathered from many nations to the mountains of Israel, which had long been desolate.” The land that is invaded can only appear to be Israel, a nation whose people have been gathering from all over the world for 50 years.
God has intended this invasion however. In vs. 16 he declares, “In days to come, O Gog, I will bring you against my land so that the nations may know me when I show myself holy though you before their eyes.” Verses 17-23 describe the exact catastrophes that will befall the invading nations. They are supernaturally destroyed and no harm is done to Israel. God will not let his people be harmed. The miraculous Six Day War of 1967 should have taught everyone that, but the world has turned a blind eye.
Ezekiel 39:9 begins the description of the aftermath. It is gruesome but also amazing in its detail when looked at in comparison to today. “Then those who live in the towns of Israel will go out and use the weapons for fuel and burn them up – the small and large shields, the bows and arrows, the war clubs and spears. For seven years they will use them for fuel.
First is the nature of the weapons. In the time that Ezekiel wrote this, burning weapons made perfect sense because they were made of wood. What of today’s weapons however? How do you burn warplanes and other metals? Amazingly, Russia has been using Lignostone in the production of its weapons. Lignostone “is a special kind of wood used for ‘coke breakers.’ It is stronger than steel, is very elastic… and it burns better than coal.” (90 LaHaye Are We Living in the End Times?) You can read more about Lignostone on its website at www.lignostone.com.
The second important part of this passage is the fact that it will take seven years to burn all the weapons. The tribulation will be seven years, so this gives us some sort of timeline with which to place this event. This event would either have to come at the very beginning of the tribulation or before to allow seven full years.
However, this event cannot happen at the beginning of the tribulation because the tribulation begins with the antichrist signing a peace treaty with Israel. This treaty is not going to immediately be broken with this battle. It won’t be until 3 ½ years that the treaty is broken. Excerpts taken from Spreading Light Ministries website.
Damascus (Syria) not mentioned in the Gog Magog war.
Isaiah 17 predicts the destruction of Damascus. Damascus is the oldest continuously inhabited city in the world. Yet the Bible predicts its complete destruction someday in the future. Isaiah 17 vs 1: “See, Damascus will no longer be a city but will become a heap of ruins. This explains why it isn't mentioned in the list of allied forces that come against Israel in Gog Magog prophecies from Ezekiel.
From the above you can see that the Destruction of Damascus preceeds the Gog Magog War and that both would most likely have to start and end before the seven year tribulation to allow for the burning of the weapons of the Gog Magog war for seven years.
Only a gap between the rapture and the start of the tribulation would allow for the prohecies to take place!
It seems to me that a gap of 3 years is most likely as it would make the total years after the rapture add up to ten years thus fulfilling the words of Moses in Psalm 90.
10 Our days may come to seventy years,
or eighty, if our strength endures;
yet the best of them are but trouble and sorrow,
for they quickly pass, and we fly away.
My guess is that the 3 year gap will seem like the start of the tribulation because Moses calls this a time of trouble and sorrow. However the start of the tribulation won't be until the antichrist has made a 7 year peace treaty... a treaty he will break half way through!