I you want to apply 迦南, the one in Kowloon Tong is the best. It is the largest one with very good facilities. The one in Hung Hom is a bit old.
When you go to 迦南 and ask for application form, they will give you a VCD which is introducing the school.
Actually, in the previous system (before 2002), BB will have test every year after 1 year old. However, owing to the new policy, BB will have test either at 2 or 3. If BB fail the test at 2, the nurse either refer the BB to see doctor or give BB a test 6 months later.
If you are worry, you can call Health Centre to book a test for your BB. However, as I know the test has been simplfied, mainly by questionair.