If you're gonna ask where you are, and if you state "I am here", you're not where you were and there's no such thing in reality as "here". We perceive "here", but we aren't there. We WERE there, but now we're somewhere else.

Why?

The earth rotates at almost 1000 MPH
It revolves around the sun at 66,000 MPH
The solar system moves through the Milky Way Galaxy at 43,000 MPH
We spin around our galaxy at 483,000 MPH
The Milky Way is moving through space at 1.3 million MPH

As my astronomy teacher put it "You will never be in exactly the same place you are now."

No such thing as "here and now", because once we say it, it's "there and then". But if we travel back through time, we'll have to travel back through space as well or we'll end up in some rather inconvenient locations.