4 year olds typically go to pre-school/day care but this is not free for some provinces. it's usually half day, either AM or PM class and sometimes only 4 times a week
5 year olds go to kindergarten, half day AM(9-11:30am) or PM(12:30-3pm) five days a week. they attend in elementary schools and is free, i think you only have to pay for school supplies that the kids will use.
kids start elementary school at 6 years old, usually from 9am-3.30pm or 8.30am-3pm