There are two options available to control when your product can be delivered: Adjusting your business days (The days your store you will actually ship the product) and adjusting the weekend delivery days (The days the carrier will actually deliver the package).
Business days
You can configure business days in the Settings section of Arrives By
How this works
Let's say your default delivery time is one day and your business days are Monday to Friday.
If a customer places an order on a Wednesday, then they can except delivery by Thursday. If they place on order on Sunday (not a business day), then they can expect delivery by Tuesday.
Weekend delivery
You can configure weekend delivery days in the Settings section of Arrives By
How this works
Let's say your default delivery time is one day.
If weekend delivery is enabled for Saturday and Sunday and a customer places an order on Friday, then they can expect delivery by Saturday.
If weekend delivery is disabled for Saturday and Sunday and a customer places an order on Friday, then they can expect delivery by Monday.