By the way,

if you do not leave U.S. immediately, you can not withdraw the B2 application, otherwise you status will be a problem. You can go to China anytime to get the H1/H4 visa after the b2 approval. The B2 approval will not affect the H1 approval notice and please note that the h1 approval notice does not equal to your h1 status because this h1 approval notice has not I-94.