It's extremely unlikely that a study permit will be issued for pre-school. The earliest you might be able to start your child would be junior kindergarten.
Note that the study permit will not allow you to accompany your child to Canada. The study permit will not allow you to live or work here. You will have to find a guardian who will take care of your child while your child is attending school in Canada.
To be approved for the study permit, you will have to demonstrate that you have enough funds. Expect school tuition to be around $14K each year. You will have to show additional funds to cover living expenses (food, housing).