Bfp on saturday?

So I have a 6 days sooner test I'm waiting to take, my friends birthday is Saturday and she wants all of us (her friends) to go out with her Saturday night for a girls night on the town drinking. I haven't exactly told anyone me and my SO are TTC. I would really love to go but obviously I'm worried about if I'm pregnant. Saturday would be exactly 6 days away from AF assuming it comes when glow says. Last month it came a few days early. My cycles are between 30-37 days. I guess my question is if I take the test Saturday would it be accurate? If a BFN am I good to have a few drinks that night? BFP obviously I'm not going to drink. Even if it's the faintest of lines I wont, how accurate would it be being 6 days away? And for some reason if it's a BFN and I go out and gave a fee drinks and then get a BFP later in the week would I have done something bad to the baby? Any advise would help!