The timing of when to take a pregnancy test depends on a few factors, such as the type of test being used and the timing of ovulation and conception.

In general, most home pregnancy tests are designed to detect the presence of the hormone human chorionic gonadotropin (hCG) in urine, which is produced by the developing placenta after implantation. The level of hCG increases rapidly in the first few weeks of pregnancy, so taking a test too early can result in a false negative result.

If you are using a standard home pregnancy test, it is recommended to wait until at least the first day of your missed period before taking the test, which is usually about two weeks after ovulation. However, some tests may be able to detect hCG levels earlier than this, sometimes as early as a few days before your period is due.

If you want to test earlier than this, you can consider using a more sensitive test, such as a blood test or an early response pregnancy test, which may be able to detect hCG levels in urine a few days earlier than standard tests. However, it's important to keep in mind that even these tests may not be accurate until a few days before your period is due.

It's also worth noting that the timing of ovulation can vary from cycle to cycle, so it may be difficult to pinpoint the exact day to take a test. If you are unsure about when to take a pregnancy test, it's always best to speak with your healthcare provider for personalized advice.