Fastiest way round trip within 12 hrs. to putoushan

I suggest that you take the fast bus from Shanghai to Putuoshan.
You can take the bus from Shanghai South Coach Staton or the Tourism Dispatch Hub under the Nanpu Bridge. the earliest bus leaves at 07:00.
It takes about 1 hour from the airport to any of the bus station. the bus trip from Shanghai to Putuoshan takes 4.5 hours. I suggest that you buy the return ticket before leaving for Putuoshan.