“Sometimes I Think We Sort Too Soon”… Or Do We?

I have several friends who have recently had babies, and being the awesome person that I am (just ask me!), I like to give little gifts. Also, being the super HP fan that I am (just ask me!), I like to sneak in little HP-themed gifts every now and again. Now, one would think that my dilemma would be pink, blue, or gender-neutral. No. It’s Red, Blue, Yellow, or Green.
With my own children, I have found that it is impossible to sort them into their appropriate house until they are at least 4, because if we sorted at two, EVERYONE would be a Slytherin! LOL However, I’ve come across children where it is obvious to which house they belong as soon as they are born, whereas others it takes several years for them to come into their permanent personalities.
At what age do you think sorting should be done? And, just out of curiosity, what HP-themed baby gifts have you given?
Crafty Witch Naomi (aka Nomes)