beginning
肇 centers on the act of starting something new: a beginning, an inauguration, or the first step of an endeavor.
肇 combines 聿 (a hand holding a brush, associated with writing or establishing) with 戸 and 攵 (a hand with a stick, suggesting action or striking). Together they convey the idea of formally initiating or founding something.
The top part looks like a door (戸) being struck (攵) to open it, while the bottom 聿 is a brush writing the first stroke. Picture opening a new door and writing the first character to mark the beginning.
For チョウ, imagine a chief named Chou ceremonially opening a new building: Chou -> チョウ, and his action marks the beginning.