How to translate "early for tomorrow"

Question

So I have at-shirt, and I've been wondering how you would translate it into Japanese. The t-shirt text is:

I'm not late. I'm just early for tomorrow.

My first thought was 「[遅刻]{ちこく}じゃない、[明日]{あした}のために[早]{はや}い」but I understand that 「AのためにB」means something like "for the benefit of A, B", which doesn't seem to fit here and I guess is my mistranslation of an alternative meaning of "for".

Another thought was simply [遅刻]{ちこく}じゃない、[明日]{あした}[早]{はや}い」, but I'm not sure if that's grammatical.

What is the correct way to translate this?

Answer 1

I'm not late. I'm just early for tomorrow.　　

は、日本語にすると、

遅刻じゃないよ。明日の｛[授業]{じゅぎょう}/[仕事]{しごと}etc.｝に早めに来ただけ。

というような意味だと思います（...が、違うでしょうか？）

または、

遅刻じゃないよ。明日に[備]{そな}えて、早めに来ただけ。

とかはどうでしょう？

Answer 2

My Japanese girlfriend once wanted me to translate some of these kinds of funny quotes. I translated them the same way you're trying to do, but all I ever got was confused looks. It's really hard to get this sort of humor across, since it doesn't exist in Japan.

But if you really want a fitting translation, I'd go with

遅れてないよ？明日のために早めだよ～

ため does not only mean "for the benefit", but is more general and very close to the English "for". I added よ？ and よ～ to make it sound a bit cheeky and to make it sound more like a joke, not a statement. I also used 早め rather than 早い, because we're talking about being too early, not just early.