I got it, my interview letter finally came it. Here is my timeline my DO is Jacksonville, Florida.
Sent n-400 on 4/29/08
Received NOA on 5/12/08
Received NOA for fingerprint on 5/15/08.
Fingerprint done on 5/21/08
Interview letter received on 6/9/08
Interview on 7/16/08,,,,
It almost over will keep everybody posted after interview date....