My friends and I are two New Zealanders with NZ Passports and one on a UK Passport.

Our original flight path is NZ to Guangzhou and then to Bali. On the way back it's Bali with an 18 hour layover in Guangzhou before going back home to NZ. Does the country of origin start with NZ or from the last port in Bali? If the latter, am I right that the 72 hours free transit doesn't apply? Thanks.