When Jehovah made us in the Garden of Eden... Did he know that we would end up working?

He wanted Adam to cultivate Eden and for his descendants to make the entire planet a paradise to live in.
Maybe that's why gardening means such a lot to some, and due to inherited sin, why killing and war mean so much to others.

Being omniscient, yes he did, but don't get that confused with thinking that gives us the right to blame him for the fall of mankind. That was his own doing.

Even in Eden, Genesis describes Adam (before the creation of Eve) as tending the garden.