Let’s say you ovulated a few days ago and you want to know if you could already be pregnant. Would that even be possible?
The little eggs’ journey
After you’ve ovulated, the egg has less than a day to get fertilized. So assuming that happened, your now fertilized egg goes on a journey that takes about 5 days. In those 5 days, it will go through many cell divisions and will grow to what is called the blastocyst stage. Once that happens, your egg is developmentally ready. It will hatch out of its protective shell (zona pellucida) and can find a place to implant in your uterus.
Why timing is important
The earliest this has been reported to happen was 6 days after ovulation. Most embryos aren’t that quick though, and on average, it takes between 8 and 10 days after ovulation. Fun (or not so fun?) fact: Embryos that implant late have a lower chance of making it. About 80% of embryos that implant after 11 days past ovulation (DPO) end in a loss, while embryos that implant on or before 9 DPO have about a 1 in 10 chance of ending in a loss.
Reference: Wilcox, Allen J., Donna Day Baird, and Clarice R. Weinberg. 1999. “Time of Implantation of the Conceptus and Loss of Pregnancy.” Obstetrical & Gynecological Survey