when is CD 1, really? so confusing

mr

Yesterday morning, pink spotting that turned red in the afternoon, but not enough to fill a pad or tampon

Today is the first day that i need a pad/tampon.

On glow under the Menstruation log, it has spotting as an option. so should I have logged CD 1 in glow as yesterday and put it under spotting, or do I log today as CD1 with a medium flow.

thanks in advance