It might be best to go with the generic "Party meets up at a tavern and decides to go on an adventure together" to start us off. It would give you a lot more leeway with plot direction while you learn the ropes, it provides us with a basic base of operations, and its something we're all familiar with/used to.
Still, as far as DM screw ups go, it could have been worse. I started my first campaign off by giving them a Deck of Many Things. One of them got lucky and drew the 50k XP card, an went from 6th level to 13th level. Things got progressively worse from there, and needless to say, we started over next week.