I echo everything everyone else has said and would a couple of things about planning the timing of when you want to get them butched.
If you want to do any home curing of largish pieces, you want to be slaughtering as the colder weather comes and not in spring or summer - it's too warm then for curing anything too large to go in the fridge. (Unless you have a convenient 10 deg C cave or cool room!)
If your butcher is like mine, you won't be able to book them in in December or January. (So for home-cured ham, November would be the latest to get them butched, really.)
And just in case you haven't worked it out from what everyone has said - if you buy 8-week old weaners, most breeds will reach pork weight in 4-5 months, ie, at 6-7 months old. A little longer for Kune Kunes (HH will tell you more exactly.) So if you want to home-cure a leg, get your weaners in June or thereabouts, slaughter October / November.
I'm basing that on my own, so far very limited, experience - so maybe others will jump in now and tell us both something different!