For anyone who needs to set up the title through the Toolbar some time after setting the SupportActionBar, read this.
The internal implementation of the support library just checks if the Toolbar has a title (not null) at the moment the SupportActionBar is set up. If there is, then this title will be used instead of the window title. You can then set a dummy title while you load the real title.
mActionBarToolbar = (Toolbar) findViewById(R.id.toolbar_actionbar);
mActionBarToolbar.setTitle("");
setSupportActionBar(mActionBarToolbar);
later...
mActionBarToolbar.setTitle(title);