Test your shoes, wear them around the house to see what to be alert about. Wear thick socks to stretch the shoes. Or take a sock, ball it up as tight as possible and shove it right into the tightest part of your shoe, leave it like this a couple weeks before prom to stretch the shoes.
If you see potential blisters areas, put band-aids on them before prom. Use foot pads to evenly divide pressure on your heel and toes.
Wear your shoes and your dress together around the house to see if the dress is catching on your dress. Pin it up if this happens.
Take a pair of roll-up flats, if your heels get a little uncomfortable at the end of the evening.