Symptoms won't begin until around the same time that your period is due. Also, don't take a pregnancy test until your period is due, or else it will not be accurate. As has been said previously, the biggest pregnancy symptom is a missed period.
Are you going to get the morning after pill, which is called Plan B Emergency Contraception? The sooner you take it the better chance it has of working. It delays ovulation and impedes the motility of the sperm.