Can you go buy it now.. Return it and then rebuy it?
Any other date this would probably fly but since it's BF they will probably tell you to piss off but YMMV depending on the rep.
How long before would you have to arrive to score one of these?
All depends on how popular your store is. Two years ago (before my WM expanded), I was able to snag an Xbox bundle getting there about 30 mins before doors opened. No cart, found out where the pallet was, bolted to it, used my
skills to maneuver between all the fat blobs with carts and snagged one. Since then, they expanded and I don't really bother for the door-busters anymore.