It’s a phoneto-semantic compound: the 少 stands for the sound “miao” and the 禾 points back to the original meaning of the word: awn of grain
Image credit: Fir0002/Flagstaffotos
The choice of 少 (shao) as a phonetic for /miao/ may seem odd at first, but note that the same choice was made for 妙、眇、渺、杪. There are some old Chinese gymnastics about complex initials that you can go through on wiktionary if you want to know more on why
But, in any case, if you’re interested in Chinese character etymology, remembering that 少 can stand for /miao/ is useful.
The\ meaning\ “second”\ \(as\ in\ time\)\ is\ a\ much\ later\ development\ of\ the\ sense\ of\ the\ word\.