Yes, this is completely normal. The charge will not fully post to your credit card until you pick up the phone from Best Buy and your order is marked as "complete" or "picked up."
I shop at Best Buy quite a bit, so I'm very familiar with the terminology they use for store pickup orders. Up until the day before release, your order will likely continue to say "Pre-ordered: We'll let you know when it's ready." At some point tomorrow (the day before release), your order status should update to say something like “Preparing for Pickup Tomorrow.” Then, shortly after 12:00am Central Time on release day (Friday), your order status should change to "Ready for Pickup." Once your store opens that morning, you should get the "Ready for Pickup" email.