Buy an all white dress. I know that many houses have a ceremony where you must where all white(nylons, etc). ASA doesn't allow any color on the dress. When I joined ASA I had three days to get a dress bc we had a special NM initiation (not the same as our initiation into ASA). Anyway all of us new girls scrambled to find dresses since is was after Labor Day.
Of course I don't know what house you'll get in, but I'm sure you'll get a bid. Plus a lot of summer clothes including whites are on sale. Buy one now This way you don't have to worry about this later. Of course I can't promise you that you'll get a bid in a house, but you seem to have such enthusiasm i don't see why a house wouldn't want you!!! GOOD LUCK!!!!
And even if you don't join ASA, the other houses will have ceremonies once you complete your pledgeship. But those girls can better tell you what you should wear.