We just returned from the Infinity's June 1st sailing and due to our Captains Club membership we were happily on board at 12:00pm. The earlier you get to Canada Place the lower number you get for boarding. I noticed people that were not in the Captains Club board right behind us.
You are sailing a great vessel!!! You will have the best time.
i'll be on that cruise too. I have heard from a friend that works boarding that you can check in as early as 10:30 or 11am if things are going smoothley. I will double check on when the best time to beat the crowds is for you and post it here soon. (Monday) I would find out for you right now, but she is boarding people as I write this.