If you’re shipping with a high quality courier, most of the time you shouldn’t have to worry about your shipments being delayed in any way. Courier companies have come up with very accurate ways to estimate your total shipping time, and are very strict about meeting their delivery time promises if at all possible. The best order fulfillment services out there have higher than 90% success rates of on time deliveries, however, this still leaves a chance, even though it’s a small one, that your delivery could be delayed.

Go here to see the original: 
Am I Going to Hear From My Courier If My Shipment is Delayed?