Post Battle of Hogwarts, NYPD beat cop McMillan has a strange day involving a Sicilian dark wizard. The next day a strange man shows up at the precinct looking for information, a British Auror named Hengest Yaxley.
There is no better place to buy a wand than Ollivanders, and innumerable wizards and witches purchased their first wands there. Including a young Albus Dumbledor.