I am currently working in USA on H1B. I have been admitted to PhD program and offered assistantship as funding. The program starts on 8-Sep. I have applied for COS using I539 on 3-Jul to the VSC, received acknowledgement dated 7-Jul. I requested for expedite on the case on 29-July but it was rejected. I don't expect to receive approval in time to give notice to my company and join school.

If I defer admission and receive a new I20 with start date as 1-Feb-2010, can I use my current I539 application with the new I20? If so, what information do I need to send to USCIS? Also, if USCIS approves my application (with the old I20 start date) while I am in the process of deferring admission and the new I20 has not reached them, is there any procedure to avoid or redress this situation?