You can consider the following measures:

1. Notify customers in time: You can send customers an email or SMS notification to inform them that the stock is sold out and give them a solution.

2. Pre-order stock: You can accept the customer's order, but do not ship until the stock arrives. This ensures that you can ship to the customer in time when the stock arrives.

3. Purchase inventory: You can purchase inventory as soon as possible to meet customer demand. When purchasing inventory, you can consider using fast shipping methods to replenish inventory as quickly as possible.

4. Provide alternative products: If you cannot replenish inventory immediately, you can consider providing alternative products to meet customer demand. When providing alternative products, you need to ensure that the product can meet customer needs and is reasonably priced.