EDIT: Step 0, pray to Arceus that I will be able to unlock all the music relatively quickly and easily without having to wade through Spirit grinding to get to them.
Step 1, Before aaaaaaaaaaaaaaaaaaaaaaaaaanything else, input name, adjust controls, and other settings.
Step 2, adjust match settings (including items and possibly random stage select). Hopefully, they'll stay saved this time around instead of always resetting back to default like in the other games.
Step 3, Amiibos. Miis fighters are first, because that's who I'll be using to unlock everyone if it'll let me. not sure about the rest, though.
Step 4, Mess around with the My Music thing in preparation for my edgy OC fanfic.
Step 5, proceed to Super Smash Bros: Infinity War "World of Light"