According to WebMD, the fastest sperm can get to a fallopian tube is about 30 minutes, meaning that the quickest conception could occur following sex is in the half-hour range . This means that, following sex, the egg could be fertilized before you've gotten up to get a drink of water.
According to Harms, conception can occur as many as five days after sex or possibly longer, as strong, healthy sperm can survive for about that many days (and perhaps even longer) in the supportive environment of the fallopian tubes as they wait for an egg to be released, if one isn't already present. Here's how it works: Fertilization happens in one of the fallopian tubes, which carries an egg from an ovary to the uterus. It can take up to seven days after intercourse for sperm and egg to join and become a fertilized egg. Usually, it's because the sperm gets into the fallopian tube before the egg is released.
Here is more from Answers.com contributors:
Yes, there is a chemical attraction to the egg, the egg has a protein sperm swim towards.
I would say at least a couple of hours, but it could take up to three days. Depending you your body and where the egg is in the cycle.
I THINK IT TAKES 2 TO 3 DAYS DEPENDING ON