The Apple Watch will be available for in store previews and Try-On appointments starting on April 10th. The Apple Watch comes in a variety of sizes, colors, and band-types which can make the decision of how to pick a band and Apple Watch combination complicated.
Apple, however, will not allow customers to try arbitrary mix and match options during their Apple Watch Try-On appointments, presumably in the interest of time and simplicity. According to retail training materials MacRumors received, Apple specifically states that they "will not size links or swap bands" at the Try-on table or Try-on cases. Try-on appointments for non-Edition Apple Watches are meant to last only 5-15 minutes. Apple will have 18 specific Apple Watch combinations on display at their Try-On tables and 10 specific combinations at their Try-On cases.
Apple Watch pre-sales and try-on appointments start on April 10th, and the official launch of the Apple Watch is April 24th.
Article Link: Apple Won't Allow Swapping of Bands at Apple Watch 'Try-On' Appointments