夙
シュク, つとに, はやい

bright and early, long ago, early in life

JLPT0 G13 S0 F5000

The relevant oracle bone form of 夙 shows it to have been 月 moon (→ evening) + 丮# kneeling figure with arms extended → predawn labor → *early* (in the morning). Also, *fast* (← be/finish early ← early) and *long ago* (← early point in time). Compare the transition from early morning darkness to the idea of early/fast in 早.

[Full Kanji Etymology List]