回复：急问, H1B 延期办的过晚,怎么维持中间时间的身份?

I don't think it will take 50 days to get the receipt notice. Once you send your application, it will take less than a week to receive the notice. That is only based upon my own experience dealing with NSC not CSC. I am not so sure if you have to receive the exention approval to continue your work. Good luck.