I got an RFE this August. It was mailed out 8/3/07, and I got the email notice on the same day. However, I physically received the RFE letter 10 days later. The due date on my RFE letter was 10/3/07.
It might be different on your case. My EB1A is at TSC.
I heard some people had 90 days to reply the RFE, while I only got 60 days.
To reply the RFE, you mainly need to gather more independent reference letters.
Good luck.