If I understood everything correctly, looks like my ecpm drops going into the second day, so I trimmed the lesser creatives - duplicated campaigns and raised the bid; obviously to no avail.
Looking back this pretty much has happened to me on every profitable campaign I had so far. I am either not aggressive enough with the number of duplicated campaigns or my bid increases. Maybe I should not be concerned with the ROI in the beginning but more with my ecpm; but that doesn't seem a very viable strategy in the long run either.