How long does underwriting process take with FHA loan?

I submitted all my info to the lender on April 2nd. I recieved confirmation from the processor that she sent it to underwriting on April 9th. I set my closing for April 30th.. Now since it is now with the underwriter, how long will it take for me to get a answer back about my loan.? my lender requested additional info from me prior to sending it to underwriter, hoping that would speed up the process . Whats the normal wait time ?