The tribulation period, as Dr. Mark Hitchcock sees it (as do most scholars), is divided into two segments.
The seven years of tribulation starts when the antichrist makes a treaty with Israel. It does not necessary start right after the rapture. There could be a short or a long time gap between the rapture and the start of the tribulation.
At some point in time, this antichrist figure will come on the scene and make a treaty with Israel which will trigger the seven year period of time. But it's divided into 2 halves - a first half and a second half to it. Dr. Mark thinks that in the beginning of the tribulation, Israel is going to enjoy peace. This will be a time of world wide peace.
Yet, at the mid point of the tribulation period, there will be events that unravels which will trigger the antichrist to take over the world. The antichrist will break the treaty and start persecuting the Jewish people. . For the next three and the half years, he will dominate and rule the world, and it will be a reign of terror.