if you will read beginning w/ matt. 24:3, you will see that Jesus was answering questions of his disciples about the future .... they asked, "what shall be the sign of Thy coming & the end of the world?"
("world" in gk. "aion", meaning "age").
Jesus then began answering these questions referring to the future in verses 4-51.
Jesus says, false prophets will deceive many, there will be wars, famines, pestilences, earthquakes in diverse places, but the gospel of the kingdom will continue to be preached.
beginning in vs. 15, Jesus speaks of the last 7 years before the rapture ...
vs. 16-26, He speaks of the great tribulation (the wrath of satan) .....
then beginning in vs. 27-31, Jesus speaks of His 2nd coming... & the rapture of the Saints.
vs. 34 that you refer to in your question ....
Jesus is not referring to the time of the disciples ... but a time in the future ....
Jesus is telling his disciples that the generation who experiences the things He has just explained to them in vs. 14-26, He will come back (specifically, vs. 29-31).
so YES, of course He knows when He will come back.
He gave us a timetable in scripture.
WE are the generation who will see these things.
WE are the generation upon whom the ends of the age have come.