Relative to what?
The rest of the Universe
While the rest of the Universe is also moving relative to Earth
None of any components of the Universe are in the same place from second to second
If setting the destination of this fictional time machine takes 3 seconds you will need to allow for the movement of the Universe during those 3 seconds
In fact (not fiction) you have to be EXACT and not even a nanosecond out
There is ZERO tolerance within the reality of so-called time travel
The ONLY way any of us will travel to the future is to live until we get there
So far as going BACK the saying ' been there done that ' and no do over applies