Answer:
age doesn't matter. some are 8 some are14 be4 the start wearing bras. all my friends and peers where bras but i don't because i don't exactly need one even though im 12 my and my friend are the same age. if you are under 10 or under and need a bra i think you should wear a sports bra they work good and people wont stare at you. if you are 11 or older and need a bra i say go a head a get a cup bra. they start in a super small size and go to super huge. there is no rule when to start wearing a bra in Canada but basically when ever you need one and are comfortable wearing one. if U aren't comfortable wearing 1 but U you need you should wear a sports bra no matter what age u are. a sport bra is very comfortable.
Hope this helps!
source:
experience from a 12 year old