Then it occurred to her what she should have said in the first place.

Exactly what I meant to say in the first place.

That would have been the thing to say in the first place.

And you could just as well have said so to me in the first place; why should I mind about your friends?

"Why did you not say this in the first place?"

No, it can't make up for saying the word in the first place.

If his account is not true, why would he say it in the first place?

No, those things should have never been said in the first place.

Now we have to worry if something has been said in the first place.

Why the hell didn't you say so in the first place.