Question: how soon after ovulation do you know you're pregnant?
Answer: While you may get a positive POAS test at 3 weeks, it's a good idea to wait a week or two and test again to confirm. A blood test also can detect hCG and is more sensitive than a urine test. Since it can detect pregnancy as early as 6 days after ovulation, you could be able to confirm your pregnancy at/around 3 weeks.