welcome to hcm
test may five false nagative results for about 3 weeks calculated from the day of ovulation taking all the delay into consideration.
from the time of intercourse its not of much value to calculate the pregnancy
and dates as its not that accurate.
take the ovulation day that is when ovum comes fertilization i. e. 14th day of menstrual cycle
than you can add up 3 to 5 days as sperm can survive inside to fertilize the ovum for this long time than if fertilization occurs it take about 6 to 12 days for implantaion so we will take 12 days here as max data. and again after implantaion it takes about 2 to 3 days for hcg kit to detect it as not very sensitive so here total add ups are 5days+12days+3days=20days
so i said average of 3 weeks for hcg to get true positive results.
hope u try to understand this calculation if not than just remeber 3weeks maximum to get positive results and least will be 7 to 9 days for hcg to become positive.
dr vikas poddar