The first test I took was at 12 dpo and although it was indeed positive, I didn't believe it at the time because it was so light... Could have been because I hadn't held my pee, didn't sleep the night before. 13 dpo was a definite light positive, again with no pee hold bc I was up the whole night sick. 'Morning sickness' began straight away with me.
So, first positive (also the first test I took, maybe would have tested positive sooner) was 12 dpo, or '3 weeks 4 days' I believe?
Should add, they were 25 miu tests, so not first response.