by jjeagle
You flip from side A to side B of a quest card immediately, once you have carried out any instructions on side A. Reference, rules p.5:"Side A is the back of the card,
and provides story and setup information. After reading
and following any instructions on Side A, players flip
the card to Side B. S"
You complete a stage (i.e. progress from side B to the next quest card) as soon as all conditions for completion of that stage are fulfilled, regardless of where you are in the turn sequence. Reference: rules p.22.