Did you even bother reading the dilution sticky all the way through.

Water is not the preferred liquid. There are specific amounts of fluid to consume. You don't want to over do this if you already have 3 weeks clean and risk getting a negative dilute. B-12 is the wrong vitamin. If your sushi contains 6-8 ounces of meat then maybe. It isn't advil, it is aspirin and you should use it and the tums/rolaids.

As far as whether or not to smoke with your friend that is on you. Try to find a home test somewhere else because they are out there if you want to know whether to delay or not. If you aren't subbing you better waitfor the results.