Walmart typically does not charge your payment method immediately when you place a preorder. Instead, they place an authorization hold on your payment method shortly after the preorder is made to verify that the payment method is valid and has available funds. This hold temporarily reduces your available credit or bank balance. However, the actual charge is generally applied when the preordered item is shipped or picked up for delivery. Key points:

• Authorization holds happen soon after preorder placement, but this is not the final charge.
• The definitive charge usually occurs once the item is ready to be shipped or delivered.
• If a preorder item is delayed or backordered, Walmart usually does not charge you until the item is ready to ship.
• In some cases with gift cards, PayPal, or debit cards, charges may happen immediately.
• If you cancel before shipment, the charge or hold is typically voided or reversed.

So, in summary, Walmart charges for preorders mostly at shipping time, not at checkout, with some exceptions depending on the payment method.