How long before i go for finger printing?

I sent in my adjustment of status application May 1st. May 27th i got the receipt. I have yet to get an appointment date for my finger printing. Normally i wouldn't be concerned, but my mother also petitioned for my stepfather and he also applied for adjustment of status. In two months he went for his finger printing, got his work authorization and social security and also got his interview appointment. I don't understand why his was so quick and mine so slow. Any thoughts?