First thing: nowadays, you don't ever get a WTR when you have applied for Residence under SMC. That is the old name. Since November 2010, you might get a
Skilled Migrant Category Job Search Visa (SMC JSV), otherwise known as
Deferred Residence.
If you are on that visa,
whenever you get a skilled job offer (even if it was 8 1/2 months after you got to NZ) you can immediately take your offer to INZ, and they will activate your Residence. If it is just the offer and contract you are showing them, or you have not worked in the job for three months yet, they will give you Residence with a Section 49(1) condition on it, which is that you must work in that job for three months, then you can go back and get the condition lifted. If you go when you have already worked in the skilled job for three months, then they will give you your Residence without conditions right then.
http://www.immigration.govt.nz/opsmanual/30614.htm