Every station has regular delivery sweep times throughout the day. STL has a 7pm sweep time for example. The delivery company has 6 hours from that sweep time to get the bag to the customer. For special deliveries, the 6-hour window begins as soon as the Baggage Delivery Order is printed.

When a BSO agent says your bag will be out for delivery at noon, that means 6pm should be the absolute latest to expect your bag. It would only take the maximum 6 hours if there are a lot of bags to deliver (like during the August outage), or if you live a couple hours from the airport.