Soon, but not exactly when.
I'll visit you one of these days when I have more time.
我会在这些天中的某一天有时间的时候去拜访你。
If things continue like this, something will happen soon.
If you keep acting like that, one of these days you'll get in trouble.
如果你继续那样做,迟早会惹上麻烦的。