I looked it up on google and the average NHL hockey game lasted 2 hours and 19 minutes so you should be on your way out the door somewhere between 9:10 and 9:30 pm.
http://www.nhl.com/nhlhq/cba/relaunch_faqs072205.html
Is there not concern that with the expanded overtime format, games will run too long?
No. With the addition of the tag-up rule, history suggests that our games will be quicker. When the League first introduced the tag-up rule in 1986-87, the average length of our games dropped by seven minutes from two hours and 36 minutes in 1985-86 to two hours and 29 minutes in 1986-87. Our average length of game in 2003-04 was two hours and 19 minutes. So we do not expect games to run longer.