I would have to say it would depend on when you ovulate. If you DTD say 4days before you ovulate then 2weeks later you test you would still be only 10days since conception. Certainly possible to get a BFP then but you could also be pregnant and it show a BFN. If you ovulated before you DTD then your likely to be able to test earlier IYKWIM. It really would depend on how long since ovulation over how long since DTD as the sperm can live for several days prior to fertilising the egg as to how soon a test would be reliable.