Pavan,
My experience, - I have submitted my application on 1st April (2012) sometime late night and got the response on 6th April (2012) afternoon. I did not get any intermittent updates for those 5 days.
An email comes right after you submit the application - "your application is received" and after 5 days another email which says- "please proceed with your PMP certification as application is accepted."
Hope this helps!
Regards,
Sasikiran