Counting DPO?

Ok ladies, can someone explain this to me? I had some mild cramping yesterday morning (but not as intense as my typical ovulation cramps). I took an OPK around 4:00PM and it was positive. I haven't had any ewcm, just wet and watery, but I rarely get any ewcm. I know that it's impossible to know if I've ovulated for sure since I don't temp, but would this most likely mean that today would be 1dpo or tomorrow? Sorry this all confuses me sometimes!