Hi Nads, Welcome to HealthcareMagic Forum. The Ovulation occurs 36-40 hours on an average after the Choriomon injection. The Sperms remain alive in Woman s body for 24 Hours. For Example, if you have taken a HCG injection today, you should be having Unprotected sex the next day and the day after to Increase the chances of Conception. If you have Ovulated and the sperms have been released the Fertilization happens in minutes, on an average around 30 minutes. Sometimes It can take minutes for at least some of the sperm to reach the fallopian tubes where they are stored waiting for the egg to release if it has not already been released. Good Luck.