Biblical historians initially thought that Matthew would be the first to record the gospel. Thus, the Gospel of Mark was considered to be a compression of the Gospel of Matthew. However, after careful study, the Q Gospel was first recorded, the Mark Gospel was recorded, and Matthew and Luke remained almost the majority (90%), and about 5% of the remaining 10% were extracted from the Q Gospel, so Matthew and Luke's pure magnetic data were only 5% each.
So what's the date of the Gospels' record?
According to historians, it is widely believed that the Gospel of Mark was recorded about 70 years after A.D., and that the Gospel of Matthew and Luke were recorded about 15 years later. Accordingly, it is said that the Gospel of John was recorded again about 15 years later.
Understanding this order properly plays a very important role in understanding the gospel. For example, there is a prophecy at Mark 13:30 that seems to be, "I tell you the truth, this will happen before this generation passes." If the Gospel of Mark is recorded before 70 A.D., that is, before the fall of Jerusalem Castle, the prophetic effect of what was recorded and what was recorded afterwards is wide-ranging. If these words were recorded before the fall of Jerusalem, the prophecy was clearly fulfilled and furthermore, the 'one generation doctrine', which is the important doctrine of today's Watchtower, may play an auxiliary role in gaining momentum. However, if the Gospel of Mark was recorded shortly after 70 years, this prophecy loses most of its effects. At best, it is an ex-eventus. Even if this posthumous prophecy is truly Jesus' word in advance, it is too impellent to see as a model prophecy that will come two thousand years later.
Therefore, the intention of this statement is nothing more than to claim that Jesus' words have been clearly fulfilled and thus to prove that Jesus is the true prophet of God. If the date of the Gospel's record had been revealed a long time in advance, there would never have been an interpretation of this saying as an absolute prophecy that causes some kind of heaven and earth opening.