This is an interesting situation and I am not sufficiently sure of how this is best handled to give you definitive advice. I feel you should leave your application for the JSV as late as possible before the deadline. My belief is that you need to have entered NZ to activate your visa before you can be deemed to be working for an NZ employer.
I suggest you get in touch with the Case Officer who handled your SMC application, explain the situation and see what s/he says. When there is any doubt about how a rule will be interpreted, it is best to ask the person who be making the decision. Good luck!