Marvel Studios has been pretty consistent when it comes to film release and trailer release. Starting with The Avengers, every release is preceded by a trailer six months in advance. Let's take a look at what happened with The Avengers for just one moment:
The Avengers
First Trailer: October 11, 2011
Official Release: May 4, 2012
Difference: 6 months, 3 weeks, 2 days
Iron Man 3
First Trailer: October 22, 2012
Official Release: May 3, 2013
Difference: 6 months, 1 week, 5 days
Thor: The Dark World
First Trailer: April 23, 2013
Official Release: November 8, 2013
Difference: 6 months, 2 weeks, 2 days
Captain America: The Winter Soldier
First Trailer: October 24, 2013
Official Release: April 4, 2014
Difference: 5 months, 1 week, 5 days
Guardians of the Galaxy
First Trailer: February 18, 2014
Official Release: August 4, 2014
Difference: 5 months, 2 weeks
The last two, however, have been fairly inconsistent. However, Captain America: The Winter Soldier has a pretty decent explanation: Marvel was releasing a property soon that it could be attached to. However, that doesn't seem to be the case here as Marvel doesn't have a film opening up...wait...
Big Hero 6
Opens: November 7, 2014
Same Weekend as Thor: The Dark World
Inspired By The MARVEL Comic Book
This film also serves as a proper platform as well as a way in which it fits into
Marvel's typical release schedule. Out of the last couple of trailers, most of them have been released on Tuesdays or Thursdays and usually two weeks in advance of a big release (if there is one). So, knowing that I can get it down to within the three day time period:
October 21, 2014 -
October 23, 2014
Anywhere in there is where I'd put money into the fact we'll see the first trailer for the Avengers sequel.