Why don't we know? Well, part of the reason is God is exercising God COMSEC (Communication Security according to Wikipedia is "is the discipline of preventing unauthorized interceptors from accessing telecommunications in an intelligible form, while still delivering content to the intended recipients" I submit He's waiting on the Church to accomplish an assignment and he also knows that we are people, have difficulty with our tongues and "loose lips sink ships." Hebrews 10:12-13 says;
"But this Man, after He had offered one sacrifice for sins forever, sat down at the right hand of God, from that time waiting till His enemies are made His footstool."
He is Waiting Until....
His enemies are made His footstool. Psalm 110:1-2 was quoted by Jesus in Matthew, Mark and Luke where it says:
"The Lord said to my Lord, “Sit at My right hand, Till I make Your enemies Your footstool.” The Lord shall send the rod of Your strength out of Zion. Rule in the midst of Your enemies!"
When this was written the context was, whenever a king was seated on His throne, it was where He placed His feet. That was a footstool and it went with the throne.
The Church has a Job To Finish!