144 hour transit visa for Shenzhen possible?

Hi there. I'm flying from Singapore - Shenzhen, crossing to Hong Kong, then flying to Auckland (SIN-SZX-HKG-AKL) in January 2018. I can't find official information on whether the transit G for Guangdong province is available yet - I have read in some places that it's not yet available, but will be introduced soon. Will I be able to stay in SZX on a 144hr free transit in Jan 2018? And if I cross the border to Hong Kong, will this qualify as my third destination? Thanks!