No! You can get pregnant anytime you are not using condoms and/or birth control. You can even become pregnant if your partner removes his penis from your vagina before he ejaculates. This is because the fluid that comes out of the penis before ejaculation can have sperm from a previous ejaculation and it only takes one to become pregnant! Since you had sex 4 days ago, you still have time to take emergency contraception. EC is effective if used within 5 days (120 hours) of unprotected intercourse. However, the sooner you take it, the more likely it will work. Read more about emergency contraception and how you can get it.