事到临头，要沉住气。

Now that the situation becomes critical, one must keep calm.

事到临头他们却改变了计划。

They changed the plans at the last minute.

现在精心规划，就会避免事到临头手忙脚乱。

Careful planning at this stage will help to avoid a last-minute panic.

你如果没有思想准备，事到临头就会抓瞎。

If you don't anticipate what may happen, you'll find yourself at a loss when sth. crops up.

但是问题依旧存在：事到临头，他们真能一不做二不休吗？

But the question remains: when it comes right down to it, can they actually go through with it?