The writers for "Reign" season 4 have revealed via Twitter that the show has officially begun filming despite the fact that the CW Network has yet to announce the show's premiere date. According to a report from Cartermatt, it is likely that "Reign" season 4 will be intentionally delayed from its usual fall premiere and instead launch in 2017.

According to the report, the main reason why "Reign" may be delayed is to give the other CW shows that have higher ratings to be given the spotlight. Some of the aforementioned titles include "iZombie," "The 100" and "The Originals," all of which target the same audience niche that "Reign" does. 

If these shows all target a similar audience then it is speculated that the CW may want to move "Reign" out of the way and into a more suitable release window where it will not affect the other shows and vice versa. If this proves true then it is likely "Reign" will launch by early 2017 such as in March or April. 

Fans do speculate that the show will not be delayed to late April or early May as the show will need to contend with the likes of "Game of Thrones" on HBO. Like "Reign," "Game of Thrones" focuses on period-piece sets and storylines although it implements fantasy instead of real-world history.

While the two shows do not air at the same time or on the same network, they do target a small niche of audiences interested in period-piece drama and "Game of Thrones" could weaken the excitement for "Reign" season 4, lowering its already failing viewership ratings. 

As noted by TV Series Finale, season 1 managed to garner an average of 1.57 million viewers while season 2 saw a dip to just 1.08 million viewers. Season 3 saw the largest decrease as it averaged 0.983 million viewers per episode and it was widely speculated that the show might be cancelled.