Well, Jesus could not know the time of the Second Coming and still be God the Son.
That was only a temporary (volunteered) state of being.
For before he could qualify to die in our place, he first had to prove himself able to withstand all the temptations we fail to resist.
For we do not have a high priest who is unable to empathize
with our weaknesses, but we have one who has been tempted
in every way, just as we are—yet he did not sin." Hebrews 4:15
Once he proved himself to be a lamb "without spot or blemish" ...
He then was sacrificed as our substitute on the Cross.
THEN!
After paying for the sins of the world?
He no longer needed to remain as a man.
So, after he was finished, he ascended back to heaven.
When He ascended he was glorified, and RETURNED to heaven to his rightful function as God!
For in Christ all the fullness of the Deity lives in bodily form,
and in Him you have been made complete . . ..
He is the head over every power and authority. Colossians 2:9-10
We are in for something too big for our tiny brains at present to contain....