But special relativity still applies. So you can only do this by traveling at nearly the speed of light away from or towards your target. Travelling this fast is a separate power with separate side effects, and you don't have it.

The humble shroom trip:

You are also affected.

It affects your aging by 1,042x as much as the speed used. Careful, or you'll either become dust or Benjamin Button yourself.

Requires large amounts of reaction mass and plenty of space.

You can't actually change time, just your perception of time. Your muscles don't move any faster. If someone is throwing a punch at you and you slow down time, you can appreciate the fist moving at your face for an hour of your slowed-down time, but you still can't dodge the punch. If you speed up time, you still need to eat, sleep, and perform other bodily functions. So, instead of getting hungry every few hours, you get hungry in what feels like seconds. And, since you don't have super-speed, you need to slow time back down again so you can eat.

It might still be a power worth having, but it's not as awesome as it might seem at first.