Hello, Alice,
Welcome to planDisney. And, if I'm not mistaken, I might welcome you to an exciting adventure aboard my favorite ship of the Disney Cruise Line fleet: the Disney Wonder.
My family and I just disembarked from the Disney Wonder a few days ago. We also traveled to Vancouver, British Columbia on the Wonder. Our cruise started in Honolulu, Hawaii. But, since both Honolulu and San Diego, California are US ports, our situation would be essentially the same as yours.
As you are probably already aware, you will be subject to Disney Cruise Line's alcohol policy when you board your cruise in San Diego as well as any other port your ship may visit during your cruise. You may choose to bring on board either wine or beer. If you choose wine, you may carry on up to two bottles of wine or champagne. Each bottle may be up to 750 mL.
On the other end of your cruise, you will be subject to Canada's import laws and regulations as implemented by the Canada Border Services Agency. A few days before our cruise was due to port in Vancouver, our stateroom host left a Canadian Customs Declaration - E311 card in our stateroom. The declaration card includes information about per-visitor duty-free allowances. A few days before your cruise, I would encourage you to visit the Canada Border Services Agency's website to look up the latest version of the E311 Declaration Card so that you have the up-to-date information you need for your cruise. That said, I'll share that the version of the form we received indicated that each visitor of legal drinking age in the province they are entering in Canada is granted allowances for up to 1.5 L of wine or 1.14 L of liquor or quantity 24 of 355 ml cans or bottles (8.5 L) of beer or ale.
Alice, I have to say, I'm a little l envious you will be sailing on the Wonder before my family gets another chance. We have been feeling anxious to get back on that amazing vessel as soon as we can. In fact, just a couple of days after we returned home, we already booked a future cruise aboard the Wonder. We can't wait to sample the perfectly fluffy and delicious beignets in the French Quarter Lounge. And we are looking forward to watching some of our favorite shows again, including Frozen, A Musical Spectacular.
I hope you have a magical time, Alice!
~Tony