It is generally recommended to wait until you have missed your period before taking a urine pregnancy test for the most accurate results. However, some tests claim to be able to detect pregnancy as early as 6-8 days after ovulation, which may be around the 28th day of your cycle. Keep in mind that these early detection tests may not always provide accurate results and it is possible to receive a false negative. If you suspect you might be pregnant but receive a negative result, it is advisable to wait a few more days and retest or consult with your healthcare provider for further guidance.