How have you setup the internal Shipping Delivery Information and option from Shopify panel?

What I'm asking is this, for example ePacket, do you set the delivery info for customers view also to 12-20 days?

Or you just leave it something like this: Free Shipping 7 days etc.

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I run multiple dropshipping businesses and the shipping times even with ePacket is never ending problem, my idea was testing out with showing the shipping times 12-20 Days when they place the order and add information that every order that arrives late comes with a gift card / bonus code - I would generate those bonus codes for the late arrivals.. I was thinking this might solve couple problems and even helps to bring the customers back.. My problem is im afraid losing the client at checkout when they see the real shipping times (12-20 days) - Also maybe its not the best strategy psychologically to inject the idea before the sale that the order might be late.. Im not sure thats why im asking whats your take on this.. Otherwise i will run a beta test on my own method that will cost $$$$