How old should kids be baptised?
Soon after their birth, isn't it 40 days?
Then why do most people baptise them after 1 year?
Because just about every Greek I know wants to throw an almighty celebration extravaganza with dozens of people invited, after the ceremony, and such events take time to organize. I'm not being sarcastic. I've been to Greek baptism parties where a couple of hundred were present, a live band playing music, and other frou-frou normally seen at wedding receptions.
Compare this to the many Russians I know, who baptize their babies no later than three months, and most within 4-6 weeks, and have a simple get-together afterwards with the nearest and dearest.
Not only is it spiritually beneficial for a bub to be baptized early, but it's so much more practical. It's MUCH easier to do the honors with a little baby, than to fight a boisterous squirming and much larger one-year-old (and often older, yes, it happens too often) to get him into the font. And another bonus: the very little ones almost never cry, in my experience.