As long as possible; at least until the legal drinking age.
Be open & honest
Speak to your parents about drinking. It is better to be open and honest.
Try not to have more than one or two drinks at a time. Drink water between drinks- p.s. your peers don’t need to know.
Have a full stomach
Eat before and while you are drinking alcohol.
Canada’s Low Risk Alcohol Drinking Guidelines for Youth (Canadian Centre on Substance Abuse)