New to Opk

L🌷

I started testing yesterday which would be CD 8 and then I tested again today (right before me the DH had a nooner on my lunch break 😉 lol). I’m curious if it is normal for it to become dark like that only a day apart and also according to glow I’m not due for ovulation until the 31st. Could I be ovulating early? My cycles range between 26-28 with my longest so far being 29 which was last cylce.