YOU SAID:

When first you practice to deceive.

INTO JAPANESE

最初にあなたが欺く練習をするとき。

BACK INTO ENGLISH

The first time you do the practice of deceiving.

INTO JAPANESE

あなたが欺く練習をするのは初めてです。

BACK INTO ENGLISH

This is the first time you practice deceiving.

INTO JAPANESE

欺く練習はこれが初めてです。

BACK INTO ENGLISH

This is the first time I have practiced deceiving.

INTO JAPANESE

欺く練習をしたのはこれが初めてです。

BACK INTO ENGLISH

This is the first time I have practiced deceiving.