How long after ovulation does fertilization happen?
The egg is fertilized in the fallopian tube, and then travels down, and implants in the uterus. It takes about 3 days for it to get down and implant. If you had sex, and the sperm was in the fallopian tube when the egg was released, you would have immediate fertilization. It just depends on when the sperm meets the egg. That’s why some women have “ectopic pregnancy”, where the egg implants in the fallopian tube, and does not travel to the uterus.