all my girls were done between 5 and 6 months old, my eldist just turnd 4years old at the weekend and i can see no problems with her bones.
i think under 5 months is too early, our ver sugested around 6 months as it is ment to stop mammary cancer when they are older(only time will tell if thats true or not) which is what my mums cockers died of.
i ears different things some people say nutering too early stunts their grothe meaning that the frount legs dog develop to their full length, others say it makes their legs grow longer than they should.
i think it depends on your own opinion and the opinion of your vet.