The early Justice League footage and trailer have not shown Superman for obvious reasons.
Though knowledge of the trailer may be available now, it is still unclear just where Superman will pop up in Justice League since Batman and Wonder Woman have been out recruiting Aquaman, the Flash, and Cyborg.
Now word on the street is that the next trailer for Justice League will for sure feature the return of the one and only Superman.
At any rate, it is unclear when we will get to see the new Justice League trailer, but Comic-Con would be a good assumption.