Hi - it is quite confusing isn't it? I usually take it that i've ov'd the next day after my +ive opk which means the day after tomorrow would be 1dpo for you, I think, but I don't think it's an exact science. Are you charting at all as this might help. Saying that, I'm pretty sure I ov'd last night as I had quite a bit of pain in my right ovary, which has gone today and I only got my +ive yesterday... I'm taking tomorrow as 1dpo I think- oh, now I'm confused lol! Hope I haven't confused you more... xx