Well, the first day I was supposed to take it, I already woke up with huge guilt thinking about how my parents would react, all the trauma, everything. So I already knew I wasnt going to be able to follow through. So now I already prepared before hand all the audios and letters ill leave for them, once you sort through all this and have a better resolve( assuming that ctb is what you really want) than youll be able to stay calm and resolute after drinking it.
Of course, some benzos might help to knock you down faster, but nothing can replace a resolute mind. So thats the most important thing, and everything else thats holds you back from doing it( again, assuming that ctb and non existence is what you really want) must be dealt with before the set date.
As for after ingesting it, I guess that only you can know what makes you calmer, I plan on chewing some gum and listening to music. And I told myself i'll only have positive thoughts the day I try, and try to remind myself that suicide is a right of every individual.