Could be useful for anyone considering switching. It doesn't mention a minimum term to be on another network or of it can be used in conjunction with other offers like buddy codes.
T&C's
5GB switching promo terms
Porting Offer - valid from 3rd December 2018
New mobile customers only
A customer who activates a new SIM and buys a rollover mobile plan from 3rd Dec 2018 and brings their number over within 30days from activation of SIM.
Excludes Skinny Direct customers
If you are current Skinny broadband customer you can still claim this offer: if you are new to Skinny mobile.
It will take approximately 3 hours (or more) to bring your number across from your previous provider to Skinny, as long as all your details are correct at time of porting, and there are no account issues with your provider.
You may be responsible for unlock fees, porting charges and/or early termination charges to your current telecommunications provider.
Can I use my phone while I am waiting?
Yes - If you are using your new Skinny SIM, then you’ll receive a text telling you that your old number has been switched over to Skinny.
Or you can continue to use your current (non-Skinny) SIM until you can no longer make or receive calls/texts or use your mobile data. When this happens the switch is complete and you can now pop your new Skinny SIM into your phone and your number will be there waiting
Rollover data expires in 365 days, unless used prior.
Rollover terms apply.
Standard porting terms apply.
Skinny terms apply.
Bonus data of 5GB Rollover Data will usually take up to 1 hour or less to be applied to your plan. In some cases, this may take up to 1-3 working days to be applied. You must be on a $16 or above Skinny mobile rollover plan to use your bonus data. Data is a one off bonus.
I prefer warehouse mobile. They are the cheapest, they let you customize the plan not to mention standard rates are the best.
You should have a look.