自从
zìcóng · HSK 3
since
自从 = self/from + follow → 'from (a point) onwards'
自 means 'self/from' and 从 means 'follow/since'. Together they mark a starting point in time that the situation has followed ever since, e.g. 自从他来了 = since he came.
自 — pictograph of a nose
自 originally depicted a human nose, shown frontally with the bridge and nostrils. Ancient Chinese pointed to their own nose to mean 'me,' so 自 shifted to mean 'self' or 'oneself.' A new character 鼻 was later created to carry the original 'nose' meaning.
从 — two 人 (person) figures, one following the other
从 is a pictographic compound showing one person walking behind another, vividly depicting the act of following. The original meaning 'to follow' was extended to 'from' (the starting point one follows out of) and 'to obey'. The traditional form 從 added 辵 (movement) and 止 (foot) to reinforce the walking sense.