You can't file an I-485 for your family member if who
is out of USA, however,since you have got GC,you may
file an I-824 ( no I-130 ),your son may get an immigrant visa in Guangzhou,usually need one & half year,he may get GC in two weeks after he enter USA.If you use I-130,you need to wait 5-8 years since you getting GC.
