For a replacement you've already ordered, the quickest way to get a date is through the order or case itself: check the Apple Store app > Account > Orders, or the tracking email Apple sent you, and use the case ID if the replacement came from a support request. If no date is shown, contact Apple directly at https://support.apple.com/contact (choose AirPods, then the order/repair option) and give them the case or order number so they can see the exact status. Chat and callback are usually quicker than email. Community members can't see your order, so please don't post order numbers here.