Launching with any realistic commercial schedule viability commensurate with realistic Training and Checking capability in early phases; means using a third party for bulk line experience makes perfect sense. QF did it with A330 and B787 in recent times as an example.
75% line training load has been done at JQ with remaining 25% at NWK; perfectly matches the T & C resourcing compliment and sector / hour ratio between the two organisations.