A few motifs may help us structure Matthew’s understanding of time periods, whether or not he has a notion of salvation history as Luke is often said to have.
1. Content concerning after Mt 28:20 but before the escahton
My purpose is not to explain Matthew's eschatology or the events leading directly up to it (e.g., 24:36-44), but rather the time in between, following the end of Matthew's story. These passages point to the time in between: the founding of the church (16:18-19), the disciples telling people about the transfiguration (17:9), church discipline, including binding and loosing (18:15ff), gathering in Jesus' name (18:20)
2. The Coming of the Kingdom
It is clear that Jesus’ ministry is related to the coming of the kingdom of God, which is present yet also future. It seems to be related (by, e.g., the agricultural parables of ch. 13) to the preaching of the word. How does Matthew understand the kingdom in light of Jesus’ presence (and is John part of the kingdom, 11:11-12?), and how does this change with the crucifixion, with the resurrection, and with the end of Matthew’s narrative?
3. Bridegroom, Wineskins and Presence
Will the disiples only forego fasting during Jesus’ ministry? Isn’t he still present with them after the narrative as well? Yes, when they gather in his name (18:20). But what about the parables of a master leaving his servants to wait for his return (esp. ch. 25)? And why does Jesus say, “you will not always have me“ (26:11)? Surely that doesn't only mean for the 3 days in the grave. (But then, why the immediate reference to burial?) When Jesus wonders how much longer he has to tolerate the generation (17:17), is that just rhetorical? And what is the new patch or new wine –– those metaphors suggest a permanent shift from something old to something new, an idea that matches Jesus’ teachings about fulfilling the law but seems to contradict his bridegroom metaphor.
4. Authority given to men: Binding and loosing?
Exactly what kind of authority do the disciples have, and does it extend beyond the Twelve? Are they free to make decisions (e.g., by the guidance of the Spirit), or are the constrained by the teachings of Jesus and interpretations of the law according to the principles Jesus gave them? Or are they only free to grant forgiveness?
5. Gift of the Spirit
John announces that Jesus will baptize with the Holy Spirit, and at the end of the Gospel Jesus appears to authorize the disciples to do just that.