If you're allowed to go outside of the normal up dos then I recommend checking out waterlily716's youtube channel. But if all else fails I would do the bun or French Braid. Especially if it's really formal.
Good Luck(:
Type -2c3a
Low Poo-Kinky Curly Come Clean
Condtioner-Kinky Curly Knot Today Conditioner
Products- LA Sports Gel and DevaCurl Mister Right