The big problem escaping most SF writers about Time Travel..
When you travel through time, you also travel in space!
The Earth travels at 30 km/sec around the Sun, the Sun travels even faster around the galaxy....
If you want to aim at a specific moment in time, you need to know exactly where in space was the place you try to aim at. A few milliseconds error and your body is either floating in space or miles below the surface of Earth.