YOU SAID:

the last thing to do is never the first

INTO JAPANESE

最後やるが最初ではないです。

BACK INTO ENGLISH

In the first end but is not.

INTO JAPANESE

最初で最後ではありません。

BACK INTO ENGLISH

The first and last is not.

INTO JAPANESE

最初と最後ではないです。

BACK INTO ENGLISH

Not the first and the last.

INTO JAPANESE

ない、最初で最後。

BACK INTO ENGLISH

Not the first and the last.