So I did some research and found this simple rhyme on the site SurvivalSkills.com:
If you see the Moon at the end of the day
A bright Full Moon is on its way
If you see the Moon in the early dawn
Look real quick, it will soon be gone.
Well, I saw the moon at dawn during my early morning row. So, according to the rhyme, it's a waning moon.
With this new information in mind, I've made up my own rhyme. It's a little shorter and maybe easier to remember:
Wax at night, wane by day
Until the moon wanes away