So, no one knows for sure when trailer will drop. The possible dates are currently October 9th, 10th, 15th,16th, and 19th. Breznican from EW (who has had a lot of exclusives with Lucasfilm / Disney) tweeted that he was pretty sure it was this month, but that now he's heard it is going to be pushed back to November. Jordan Maison from Cinelinx reported the same (and for some reason Jason Ward from MSW, the guy who gave us 90% of all confirmed leaks, thinks he's legit).
At any rate, it's odd that the trailer has taken this long to be released. Most major films get their first full trailer (not teaser) a good 4 to 6 months in advance. We are currently a little more than two months away from the premiere, and the marketing for the film seems to be mostly region locked (some people report lots of posters, toys, etc, others are reporting nothing), and it has felt a bit downplayed. I guess they are trying to lower expectations, and let Spectre and Hunger Games pass from people's awareness.
In any case, the film will do well at the box office, maybe not as well as Avatar, but certainly as well as the Hobbit.
Nothing to see here, move along.