Allen will make his first appearance with the Colts in Saturday's preseason finale against the Lions, James Boyd of The Athletic reports.
Allen began practicing with the Colts a week ago, and he is now set to see action in a game setting for the first time since joining Indianapolis earlier this month. Fellow wideouts Alec Pierce (ankle) and Josh Downs (calf) are both banged up, but both have a chance to take the field in Week 1, so Allen will presumably open the regular season as the third option at the wideout spot for the Colts.