For a while there last year I was getting full blood work up every month (now it is 3 monthly).
Doc always says to arrive well hydrated, drink as much water as I could.
Go out and wait for nurse to give me the printed appointment slip.... they always say no food or drinks 12hrs prior.
In saying that though... I wake 2 to 3am everyday, appointment is always at 9am.
I would have a black coffee no sugar when I wake............ then start pouring water down me throat for the next 6 hours.