My baby born on April 2010 and want to study at IS..pls advise

my baby born on 2010, i plan to let him entry international school instead of local school.

When should I start to submit the kindergarten application ? Coz I heard the competition is hot and most of them is first come first serve...

Beside, I live in Tseung Kwan O, any suggestion about the international kindergarten ?? (Kowloon area is also ok) Which one is better for entry international primary school in the future??? Thanks!!