Not meant to be the AFTL police, but there is a lot of incorrect info being spread around. Discretion most certainly
CAN be used before departure.
"..will apply only once the crew member has commenced a FDP..". FDP commences once you sign on.There is nothing that states that you have to be airborne, or away from Hong Kong, as someone said in a previous thread, to use discretion. Having said that I personally don't use discretion especially ex HKG.
