You can do it, but morning is scientifically much better for accurate results. Also, once you get your positive, please visit your doctor quickly to get your thyroid and other blood tests checked. Regular monitoring is very important.
I totally understand how hard it is to wait through the night when you are so anxious to know. If you must test tonight, try not to drink water for a few hours before. But morning urine is best to get a clear, reassuring result.
Yaar, you can do it, but actually the morning urine has the highest HCG concentration. If you do it at night, the line might come very faint or negative even if you are pregnant. Better to wait till morning, trust me.
I felt so impatient that I actually did my first test at 11 PM and it was negative, which made me cry. But next morning, I got a beautiful positive line! Morning urine makes a huge difference.
Please try to wait until the morning if you can. Early on, hormone levels can be very low and a night test might show a false negative, which can be very heartbreaking. Be gentle with yourself during this wait.