If you put it in the "// Before while" space, it will run once when you start your game, and won't run again until you hit Continue or Retry/Save/reset. Only the stuff within while (true)'s braces will run continuously while you're playing the quest. As for whether to put it before or after Waitdraw()...well, for this script it doesn't really matter. It should function either way. The global script you've got there should work.
So "//Before while" is for stuff that happens only once per quest? Does it happen again each time you reset, but not if you save it happening?