Xiaobaitu, Please Help: AP, H1-B and extension

I came back from China through AP (H-1B worker, no EAD) and this is the first time I used it. I am wondering whether I still can use AP (before it expires) one more time without affecting my H-1B status? One lawyer suggested me to get my H-1B (will expire next Sept.) extension approved before I take another trip with AP? I don't understand why? Do you think I should apply the EAD as soon as possible, just in case? Thank you very much.