You couldn't be considered under this scheme until both of you are at least 17 years old. I think that, from the time the younger of you turns 17, you would then have to put in the 12 months, then show the proofs mentioned in the regulations linked to here.
http://www.immigration.govt.nz/opsmanual/ Go to
Residence » Family Categories » F2 Partnership Category » F2.5 How do partners of New Zealand citizens and residents qualify for a residence class visa? and use the down arrow on the screen (just below the heading) to go through all the subsequent relevant pages down to F2.40.
There's no such thing as a 'partner visa'. Being sponsored by a partner is just ONE route to qualify for (in this case) Residence (there's a partner-sponsorship route to a Temporary Work Visa, too). The Residence which someone gets by this route is the same Residence as e.g. via Skilled Migrant - it gives full rights to be part of NZ society. A Resident can study, work at anything, start a business, or opt out, and can use the NZ Health Service on the same terms locals do. (Notice, though, that a Resident is not eligible for any student
grants until they have been in NZ with Residence for two years. So, with Residence, you would immediately qualify for domestic rates, but would not immediately get any help from NZ with financing the course(s) - you would need to sort that out for yourself.) Also, after two years as a Resident, if all necessary condtions are met
http://www.immigration.govt.nz/migra...nts/nextsteps/, the person can obtain Permanent Residence.