Billy has absolutely no delusions; he can hardly imagine living up to any of Chris's parties, but he's still going to try to throw the best party he can for Tony.
He's spent most of the day getting ready (having ordered Tony elsewhere for most of it), with help from friends and Kurt as the decorating lead. Slowly, his cottage transforms from an obviously teenage-inhabited home to a party home worthy of Halloween, and what they lack in black lights and smoke machines, they've made up for in Halloween-themed decorations. It's exactly the sort of party Billy's happy to be throwing.
A blue stuffed spider won at the carnival a week earlier is strung up by two ties blocking off the staircase going up to his bedroom along with a clear Stay Out sign, but the rest of the cottage is free; all his valuables are in his room, but with all the windows and doors wide open, the two rooms and area around the cottage is more than enough to entertain others.
He just hopes that he isn't being upstaged somehow, and that everything goes off without a hitch.
[Wibbly wobbly timey wimey: the party starts at sundown, but you can say evil toys attack any time after guests start arriving and mingling withing your threads. Please see
this post for more info, and
this page on what Billy's home looks like.]