2nd day late on my period

Pip • Pregnant with a little boy • c-section is booked for 4th July 2016 at 8am ✨
I've had stomach and ovary cramping the last week or so. This is the second day late on my period. Last night I went out and had a bit to drink. I'm off to the shop now to collect a first response pregnancy test. Shall I take tonight or in the morning? And will the alcohol in my urine effect the test answer to whether I am or aren't pregnant. I have extremely sore boobs also and nipples seem darker then usual.