If mum cannot be approached/unsocialised
As neonates (<4 weeks old), their best chance for survival is to remain with mum. If the kittens are safe and warm and don’t appear to be in distress, it can be the better option to leave the kittens and monitor their wellbeing from afar. Keep in mind that your presence may keep mum away, so try to monitor from a distance.
Once they reach a few weeks old, you should bring them to RSPCA for ongoing care and rehoming. RSPCA ACT has incredibly dedicated foster carers who can provide neonates with incredible care. Kittens are sent in to foster care until they are at an appropriate age for their vet treatments and mandatory desexing.
If you have monitored the kittens for six hours and the mother has not appeared for more than six hours, it’s safe to assume she will not return and you should bring the kittens to RSPCA ACT or a vet.