How early could implantation happen ? could it happen so early that i could get a positive home pregnancy test 5 days afyer intercourse?

Nature: No. It takes one to five days after intercourse for conception to occur. Then is there is a new fetus the baby has to travel to through the fallopian tubes and get into the uterus to implant. Then is has to grow big enough to have a placenta, blood, and chemicals that the mother's blood can detect. Only then, about ten to fourteen days after conception, can an HCG or pregnancy test be positive.