PERM Audit and H4 EAD

Hi,I will appreciate if you can answer one immigration query I have:Here are the facts regarding my husband’s immigration status:Currently on H1B - already used 4 years 2 months of total 6 yearsApplication for PERM - ETA Form 9089 - filed on September 21, 2014Case picked up for Audit review - March 16, 2015My immigration status:Currently working on OPT which will end on July 22, 2015H1B not picked in lotteryMy query is: What is the earliest time my husband can apply for my H4 EAD?Regards,Pooja