It all depends on what you have subscibed to. I only have GameCentre Live based upon having a new Ignite Internet package and no pre-season games are available. The season begins Oct. 7. If you have Centre Ice, there should be some games available. Keep in mind though that GameCentre Live and Centre Ice are 2 different services.
In the 2015/16 season, approximately 90 games will be GamePlus games, including approximately 50 regular season games, the complete Stanley Cup Playoffs series, the NHL Winter Classic, and the NHL All-Star Game.
Your subscription gives you access to over 1,000 NHL games during the regular season – pre-season games are unfortunately not included, as @JohhnyRockets indicated above.