Many pregnancy tests suggest taking it on the first day of missed menstrual period, but ideally, this test should be done after a week of missed period. This is because pregnancy hormones of some women develop late compared to others. Hence, pregnancy test may not be accurate when done during the first day of missed menstrual period.
When collecting urine, the sample should be tested within 15 minutes or less. Give time for the pregnancy test kit to work but make sure it follows the package instructions provided. If you want accurate results, the urine should be collected in the morning because this is the time where it is most concentrated.