Noon at the absolutely earliest to book a flight.
You will go through Canadian Customs getting off the ship, 45 minutes to the airport, then Security as well as US Border Control in the Vancouver airport. Lots of folks are going to tell you they made one mid-morning and yes, it can happen but why spend the last day of your vacation fretting about making your flight.
Sorry just re-read your post and you're asking about time of disembarking. It probably starts around 8:00 a.m. so if you want to drag all your own luggage off the ship yourself, you can opt for self-disembarkation and perhaps be off by 9:00.