When does the production of hcg begin After fertilization of the ovum?

HCG is produced once the embryo has implanted.. Sperm and egg meet in the fallopian tube, then travel down the tube, that takes about 5-10 days then the embryo implants in the uterine lining and begins producing HCG. you can usually get a positive home test anywhere from 7-14 days after ovulation, but to avoid false negatives 14 days is recommended ~pawsalmighty