"Ships in 3-5 business days" is not a date. Shoppers have to do the arithmetic, and they get it wrong. This puts the date itself on the product page: "Estimated delivery: Thu, 10 Sep - Tue, 15 Sep". It comes from your processing time, shipping range and daily cutoff, skipping weekends and the holidays you list. The clock is your store's, not the visitor's. Only the UTC offset comes from the page, so a cached page cannot freeze the cutoff countdown.
In store pickup and local delivery date picker & time...
Provide alternate delivery locations for your customers...
Enhance Checkout with Hold-at-Locations and Access Points