You can test when you are late for your period. The box should recommend taking it in the morning with your first morning urine.

Good luck.

Well if you are one day late and you had sex 25 days ago it could be possible that you arent pregnant. Not sure though.. Im only going by the ovulation calcultor, asuming that you get your period every 28 days. A test would tell you for sure.. They say to test as soon as a missed period though some can detect earlier.. Wait a few days and test again with the first morning urine. It contains the most concentrated pregnancy hormone.
Good luck!!

one day is not considered late neither is 1 day early considered early..Cycle vary time to time by 1-3 days nd is considered normal. Test agin tomorrow if it still neative I doubt your pregnant.