Short answer: Combine with savings, First Home Grant, family gifts, and First Home Loan. Multiple sources together.
You can combine KiwiSaver with savings, the First Home Grant, gifts from family, and the First Home Loan. KiwiSaver rarely covers the whole deposit by itself. That is normal. The system is designed so multiple sources combine to get you to 5% or 20%.
Kiwi Saver: $20,000
Savings: $10,000
First Home Grant: $5,000
Family Gift: $5,000
Total Deposit: $40,000
On600k House: 6.7% deposit