There's already a reading-order tag that seems to be quite popular. There've also been a few questions (like this one) that are about the order to view a long series in (in this case, Dr Who). It seems obvious to me that if reading-order is a valid tag (and it seems that it is), then viewing-order would be equally valid (although I don't have enough rep to create it myself).
Should somebody create a viewing-order tag, or are reading-order and viewing-order similar enough that they should be combined into a single tag, like 'chronology' or something?