Obie and Ophie are 15 weeks old now, and a gorgeous pair of utterly mad, purry balls of hair 
They are chipped, but not yet neutered, and obviously they can't go outside until they have been done. But they are getting faster and sneakier by the day and sooner or later are going to make it outside! (The garden is pretty secure fora month or so as high fences)
I believe they can be neutered quite young now, but while Obie (boy) is already nearly 3kg (they are Maine Coons and he's greedy!) Ophie (girl) is 1.9 and much dinkier. I don't want to stunt their growth by neutering too early but I suspect Obie will be full of testosterone soon going by his current dominance!
So how soon to safely put them both thro it?