B&H generally does not take pre-orders until they are notified that a shipment is imminent.
They told me it's because Canon hasn't confirmed the price yet. I heard that there were incidents where their pre-order price was lower than the manufacturer's final price and they didn't ask the pre-order customers to pay the difference.
B&H has not taken pre-orders in the last few years, at least. They usually take orders less than a week before a new model arrives.
Even Adorama is not taking them. They have said its because a price hasn't been announced, but they were taking phone only orders from previous customers and the price was $9999 as a place holder because a firm price was not set.