Are you sure that Steam is preloading it, or are you just guessing?
Anyway, I do agree that most of us are having heart attacks of anticipation now. If I remember correctly, my Wasteland 2 code, to be reddeemed either in GOG or Steam came more than a week before the launch date. So, I agree that it is taking some time for them to give us the codes. But I also agree that there is still time, and we are just freaking out too early.