Hi, I'm from Poland and in Catholic tradition here we do something similar.
It doesn't take long, the priest will just walk around the house with the holy water and bless the rooms. Make sure they're relatively clean. It's also custom here to give something to the priest for his troubles of coming down, but I don't think you have to. It's usually just a nice gesture.
>My family isn't religious and my mom is agaisn't all thing arab (the priest is lebanese)
Maybe he will be able to change their minds tonight, God willing. :D