Bleeding

I got off my birth control last wednesday so me and my boyfriend can try to have a baby. We already did it twice since wednesday and i wasnt sure how fast it worked so i had a little bit of beer last night. I woke up this morning and now im bleeding. My next period isnt until 10 days could it just be early? or could something be wrong? i dont think pregnancy works that fast especially since ive been on bc for years.