Hm. Well, typically a fertilized egg must travel and implant and that takes a few days. After that, the hormones will begin to increase that would register on a pregnancy test. Occasionally women will have some bleeding when a fertilized egg implants but that is not for a few days------------ and sickness associated with pregnancy happens because of the hormones. Morning sickness started for me at around 6 weeks pregnant which is the usual time it begins. I think this is a fluke, to be honest.
Use protection and be safe.
When I got pregnant I knew the next morning - I woke up sick. I recommend to do a home pregnancy test if you miss/are late for your period...and you should always use protection. Even if you don't get pregnant, you could catch an STD.