How long does it take to get a certification letter from the VA for the post 9/11 G.I. Bill?

I applied for the post 9/11 G.I. Bill on the VONAP website on Wednesday, 3 hours letter I got a email stating "the VA downloaded my claim and they will contact me shortly". How long will it take to get my certification letter in the mail? The deadline for enrollment at my local Community College for the Fall quarter is August 11th. Will I make it on time? Thanks!