There isn't any particular schedule which is supposed to be followed, but the production company generally makes use of whatever resources it gets to maximize the marketing of their film.
First of all, a press conference, or press release or news slot announces the movie and (if any) cast have been finalized along with more information about the movie as to the director, characters, etc.
Then there may appear teaser posters for the same movie, generally at periodic times.
Then in most cases, in a press conference or release of some other event for the same production house, more information is provided as to how the movie is progressing. Generally the movie crew interacts with audiences.
If there is any fan event, such as comic-con, then the movie is promoted at such events.
Periodically, the director or producer will talk and interact about the film, its production and other aspects.
Teaser trailers, TV spots will come out at regular intervals to keep the audience interested about the film.
Tentative release dates are declared.
Once a significant portion of the film is complete, the trailers and TV spots are scheduled. These are the final trailers of the film and come along with the release dates.
As the release dates come nearer the shooting is wrapped up into post-production. The stars, director and other ensemble cast try to promote the film through media, and other appearances. The production house amps up aggressive marketing by increasing the amount of tv slots, ads etc. given to the film.
Finally, as the film is being completed, it can be sent to various film festivals and competitions.
A special screening is kept for the production house and ensemble cast (in some cases). Another special screening is kept for the press and other members. The red carpet event comes at the movie release time. Mostly, the first public previews are shown to press, critics, reviewers and VIP personnel.
The release date can be different in different areas of the world, and depending on the production, some or most of these marketing events will be repeated at some regions.
Following the movie release, the ads and trailers will be changed accordingly. Also the stars and other crew members will promote the film through media and talk shows etc.