OYAP the Ontario Youth Apprenticeship program allows students to start training even when in high school! You must be at least 16 years of age and completed grade 10 in order to enroll. You will still need to eventuall complete your OOSD requirements. When you sign up with OYAP the registration fee is waived for the apprenticeship. Talk to your coop teacher about a placement and a possible community partner.
Bonus- The government provides loans for tools when enrolled!
Here are some useful links if you are considering Apprenticeship.