i used to study in an international school.
i start going nursery at age 2, kindergarten at 3 and 4. LOL

my mum told me after i attend classes in the morning i attended playschool because i was active and refused to sleep during the noon. LOL
started grade 1 at 5. LOL!

i think it really depend on the child him/herself.
and i didnt grow up in malaysia. LOL

if your child is the hyper type then why not send him/her to kindy earlier? they can learn things faster that way. i remembered my kindy taught us how to swim and draw using my creative which is splash art. still loving it. <3
but of course, dont force them if they cant. like my sister, she is more a home person, so my parents only send her to kindy at the age of 4.