“不是不报，时候未到”的英文怎么说？

matter 

n.事情；事态；问题；关于...的事情；物质；重要性

It's like they know it's only a matter of time.

他们好像知道这只是时间的问题。

a matter of time

If you say something is a matter of time, you mean that it is certain to happen at some time in the future. 

只是时间问题，用于说明某事必定发生; 迟早，不是不报，时候未到。

It would be only a matter of time before he went through with it. 

他完成这件事只是时间问题。

It is only a matter of time before I am what I like to be.

我迟早会变成自己想要的样子的。

It is only a matter of time before I can speak English well.

我迟早会说好英语的。

It is only a matter of time before I get really rich.

我迟早会有钱的。