"Before he created them? Since God is outside of time, then yes. He absolutely knew, but there was nothing he could do to stop it since he had granted them free will." Nothing He could do? Are you sure of that?
He could have chosen not to create them. He could have chosen to create them under different conditions, with different characteristics. (If not, then what restrains Him? What is bigger than God?)
"Before he created them? Since God is outside of time, then yes. He absolutely knew, but there was nothing he could do to stop it since he had granted them free will."
Nothing He could do? Are you sure of that? Okay, he *could* have done something, but he wouldn't because he has chosen to grant us free will and to abide by that.