Sorry that the rewards were posted so late, the design team's schedule was messed up due to the holidays and we were actually working on this event all week.
The reason that they have not been being posted as far in advance as they used to be is so that we can spend more time designing them and get something that is more in line with current power values and what we think will be useful to players in upcoming events. In the past creating the rewards 3+ weeks before the event and posting them in game prevented us from updating or changing them during that time to be inline with what is going on in the game.
Going forward our goal is to post them either the Friday or Monday before the Conquest event.