I'm scared im pregnant as my boyfriend's precum entered my vagina? when do symptoms of pregnancy usually appear?

A positive test: Home tests have become so accurate a positive test usually appears prior to the time that one has symptoms. If you miss your period then take a home test and then in minutes you will have your answer.

Later: Chances of conceiving are still quite low. The earliest way to detect pregnancy is with a test minimum 3-4 days after implantation or ovulation but more like 6-12 days. The sign or symptom is a missed period. This is obviously very distressing so you may want to look into effective protection.