Question about differin?

i am a 14 year old girl, indian and my face is a little oily [its getting better]. i have some acne on my forhead and a little at the top of both sides of my cheeks and a lil on my chin. i have differin at home but im worried to try it. will my face get worse then better? how long will it take until my face is used to it? plus, i have banquet it 2 weeks, i dont want to have a red face by then. should i use it? how long will it take for my face to get used to it and will it make my face worse then better?