How soon after filing PERM applicant/employer get to know PERM application selected for audit through random selection?

Hello Everyone,
My employer recently has filed my PERM, and my situation like if it goes to audit then I have to go back to home country due to H1B max-out. If I get to know the status of application earlier, then I will be prepared for the travel.
How soon after filing PERM applicant/employer get to know PERM application selected for audit through random selection?
(Considering only random selection for audit, other cases could be ignore now)

Thanks,
Amby

There is no fixed timeframe to receive the audit.