Jetstar NZ FO is $131k per year base including meal and rest break compensation, overtime $155 per hour over 65 hours. Company budgets on 10 hours overtime per month for 10.5 months of the year. DTA will be around $800 per month tax free.
If you join the Turboprops with the aim of Air NZ Jet then you are stuck there for probably a decade, if Air NZ Jet is your ultimate aim and you are young then Air NZ TP job all day long. You may get lucky and get a direct entry Jet job with Air NZ after 2 or 3 years with Jetstar but you will then have many many turboprop numbers ahead of you. If Emirates or similar is your career goal then Jetstar is a no trainer. So ultimately if it is a Koru Jet you want then join the TP fleet ASAP.
You would likely get a command at Jetstar in around 4 years as well so you can take that into account t, if I was young I would get into the Air NZ system ASAP, the contract is and always will be better than all other NZ based operators.