YOU SAID:

since when has that rule ever applied to this school

INTO JAPANESE

いつからこの規則がこの学校に適用されたのか

BACK INTO ENGLISH

Since when this rule was applied to this school

INTO JAPANESE

このルールがこの学校に適用されたときから

BACK INTO ENGLISH

From the time this rule was applied to this school

INTO JAPANESE

このルールがこの学校に適用された時から

BACK INTO ENGLISH

From the time this rule was applied to this school