No one who ordered the stock models has been charged. I've been anxiously waiting myself. Someone suggested it could be because ours would ship domestically (instead of from China) so we won't see the charge until a day or two before delivery.
It may also be that BTO orders are charged/pre-authed ahead of production. I'm sure Apple can still sell BTO models. There's not that many options and combinations, there's almost certainly hundreds of people buying the same config. Nevertheless, it makes sense that BTO orders are charged a bit earlier. It may even be that BTO orders arrive after stock orders, despite being first to be charged.