how “from” and “since” meanings originated for 自 I am going through the word: 自幼 zìyòu since childhood
自 zì self, oneself, from, since, naturally, surely; private, personal
Understand 自 originally a nose symbol.
how the meanings “from” and “since” evolved for zì? Etymology?
Understand 自 originally a nose symbol

When someone identifies himself, one of the most common gestures is pointing at his own face, and the most protruding part of the face is the nose, therefore, pointing at one's own nose represents 'oneself' (自己).
自 in the sense has the same meaning as 本 (origin, source). Your action came from yourself, your voice came from yourself, You see things from your point of view, therefore the extended meaning of 'from' was added to the character '自'