YOU SAID:
I eat oranges every Sunday since I was fifteen
INTO JAPANESE
私は15歳の時から毎週日曜日にオレンジを食べています
BACK INTO ENGLISH
I've been eating oranges every Sunday since I was 15.
INTO JAPANESE
15歳の頃から毎週日曜日にオレンジを食べています。
BACK INTO ENGLISH
I've been eating oranges every Sunday since I was 15.
You've done this before, haven't you.