Contemplating how DPO Work... let me know what you do!

when do you start the count of days past ovulation? Do you start the day after you get your positive OPK? Or do you start 2 days after a positive OPK cause chances are you will ovulate in the next 24 hours ish?

So to set it straight

Monday POSITIVE OPK.
Tuesday 1DPO.
Wednesday 2DPO
Thursday 3DPO

OR

Monday POSITIVE OPK
Tuesday OVULATION
Wednesday 1DPO
Thursday 2 DPO