when should my usps package arrive is a common question for customers tracking shipments. USPS provides estimated delivery dates based on the shipping method used, such as Priority Mail, First-Class Mail, or Express. The when should my usps package arrive information can be checked via tracking updates. USPS generally meets its delivery windows, but there may be occasional delays due to weather or other factors. Keeping track of the when should my usps package arrive status helps customers plan for package arrivals.