This will be the first time I’ll be using a SIM-less phone. How will I activate my new phone on Friday since I won’t be able to simply swap my SIM card from my old phone?
I'm on T-Mobile, but did a side-by-side phone-to-phone transfer and it went as @rui no onna says. It was an easy process. If you are not doing that, my suggestion is go to AT&T support website and find the procedures that match what you will be doing.