Shopify Shipping carriers
Each shipping carrier has different policies, resources, and requirements. Make sure that you understand the specifics of the shipping carriers that you purchase labels from to avoid any shipping delays or unnecessary fees.
Carrier-calculated shipping rates through Shopify Shipping often display expected transit time next to the shipping rate at checkout, but they don't include your processing time. You can display delivery dates at checkout that include your processing time and transit time. To learn more, refer to Setting up delivery dates.