Since the hotel is free and 2 minutes walk from the airport, and you can reserve it online in advance, I would still reserve it. The value is not for a sleep, but the shower and place to change in privacy...and leave the bulk of your carry on while in the city. If you end up not using it, you’ve lost nothing. I am travelling via CAN in J to JFK at the end of Dec...I’ll keep a careful note of the time I spend at each stage and post here.