Earliest Japanese Ideophones?

From Nihongo Pera Pera!, by Susan Millington (Tuttle, 1993), p. 14:

The Kojiki, which appeared in 712, and the Man'yōshū, also compiled in the 8th century, were written in a mixture of styles, but are considered works of pure Japanese literature. References to the use of onomatopoeia in these two works are the earliest that I have found: sawa sawa (Kojiki), to describe a rustling sound; hodoro hodoro (Man'yōshū), for falling snow; moyuru (Kojiki), for rain falling; koro koro (Kojiki), for raking over salt; and bishi bishi (Man'yōshū), for a sniffy nose. Sawa sawa still exists today, with its original meaning. Hodoro hodoro is no longer used but has become hadare or hadara, referring to specks or patches. Moyuru is no longer in common use but survives as moya moya, meaning foggy or misty, and is related to moeru, to burn or glow. Koro koro, now meaning to roll over and over, is widely used. Bishi bishi no longer refers to a sniffling nose but instead means to be strict or rigid, or to snap. The ancient phrase seems to have been transformed into the modern day bisho bisho, meaning dripping wet.

The most comprehensive online guide to Japanese ideophones that I've found is here: https://www.tofugu.com/japanese/japanese-onomatopoeia/