Just go for it

You might aswell post up the initial part where the game gets set up and the ground rules are laid down, plus which characters will be involved in the game (assuming you want it to be limited to just Jon and a few others rather than something like Jon running around asking random people a 'would you rather...' question); theres no need to work out all or even any of the questions in advance, plus posting the initial post will help get the ball rolling and allow for different first questions which in turn allows for the game to be played out multiple ways. In fact not having a predetermined list of questions may be better as it'll allow for spur of the moment ideas rather than risk people feeling tied down to the predetermined list. Besides, there's nothing stopping you compiling a list of ideas as the branch is running ;)