Jesus ascended into heaven on the FIFTH day (though Thursday is the FOURTH working day in modern times, THEOLOGICALLY it is the FIFTH day, since the FIRST day of God's Mythical Creation is SUNDAY, not Monday)
Now, Jesus entered human history, according to some Fathers, at the conclusion of the FIFTH Age of human history.
"Five are the ages of the Old law...", St Methodius of Olympus
"Five ages of the world have now passed. There has entered the sixth." - St Augustine.
St Augustine delineates the ages in On the Catechizing of the Uninstructed:
1. Adam to Noah
2. Noah to Abraham
3. Abraham to David
4. David to Captivity
5. Captivity to Christ
Now, the first coming of Christ represents the definite end of all direct, earthly and Divine activity of God for human history. No longer is God present with us in a direct revelatory sense. He has, rather, left the completion of the Redemption of the world in the hands of MEDIATING Fathers: Priests and Bishops, and us, the faithful.
How appropriate then, that Christ completed His earthly ministry by leaving us, til the end of time, into heaven on the FIFTH day of the LITERAL week, even as God ended all earthly ministry of Himself on the FIFTH APOCALYPTIC day of the week.