My I-140 is pending, my wife is in OPT, but she has to go back to China for a while. how big is the chance for her to get a visa from Beijing?, if she can not get a visa in China, she need to file I-824 (Mr. Fan told me), but when can she fill I-824, after my I-140 approved or I-485 approved? Can she file I-485 before she go back? Thanks