I'm predicting a short (~60sec) teaser attached to Battle of the Five Armies, then a full first trailer (~2m30s) in May, possibly attached to Age of Ultron.
I understand the idea behind pairing teasers/trailers to Into the Woods and Tomorrowland, but I think they'd rather get the trailers out to as many people as possible ASAP rather than trying to use the lure of a Star Wars trailer to increase sales for movies that aren't going to be guaranteed successes. Hobbit 3 and Avengers 2 are guaranteed successes - a LOT of people will be seeing them, which means a LOT of people will be seeing previews for the new Star Wars, increasing buzz for the movie.
Of course, I could be wrong.