My problem was OPT expired on Aug 31 but HR took too long to finish the h-1b filing. The final h-1b filing receipt was dated on Sep 13. I did not get my h1b approval until Nov 30. School used vacation time to cover my first two weeks' salary and insurance but I lost 6 weeks salary. No questions were asked by INS at that time.
If you get approval, the new I-94 will be at the bottom of the approval letter.
Ask HR for the case code on the receipt then you could check the status online.
Good luck.