Stupid question about calculating DPO 🤦🏼‍♀️

So if I got my static smiley on the night of feb 28th I technically ovulated the next day but do I calculate dpo at night lol since it wasn’t positive when I tested the morning of the 28th

I’m basically asking if I am considered 8dpo when the new day begins or at night? Trying to make myself feel better for having negative tests 😂