Before mankind invented time as we know it in order to correct the pesky lag between equinoxes and the maths that couldn't keep up, there was the wheel of the year. This is nature's time determined by the uncalculated movements of our luminaries, the sun and his lover the moon.
Today is the cross quarter, the middle point between solstice and equinox. This is marked by the sun sitting at 15 degrees of Aquaria, an esbat often observed on the first of the month because it's more convenient and easier to remember.