PERM + I-140 experience to apply H4 EAD

Hello everybody,
I want to ask about your experience on obtaining H4 EAD based on spouse I-140. I came to US for F1 and change of status to H4. My husband is currently in the process of PERM, at the Predetermine Wage Determination. His PERM is not approved yet. Can anybody share your experience in obtaining H4 EAD via I-140? How long does it take in total?
I am unemployed so I am very looking forward to this H4 EAD