There are three woes that are not events in themselves. They are expressions of these events being particularly bad. Woes one and two are numbered as they occur in the writing down of Revelations, and Woe three is not mentioned at all. We have to deduce what it is, though that is straightforward. If you were to write the woes down as a timeline, woe two would start before woe one, even though for a time, they would run side by side. Woe to one who sees the opening of the bottomless pit, the darkness of the locusts, and the freeing of Abaddon.
This happens well into the tribulation. A terrible event for non-Christians. The next are the two witnesses, calling down calamities upon the earth at will. The story of the two witnesses ends with their deaths and their rising again. Once they ascend to heaven, the Day of the Lord starts with a great earthquake. That leaves no time for anything else to happen apart from the great harvesting of the day of the Lord. That is the third woe, even though it does not say so.