When should I ask my parents if I can paint my room?

Ok so last summer I got to paint my room and get a new duvet cover,sheets,bathroom accessories. The bed stuff was quite expensive because it was from PBteen and we just re decorated our living room with practically everything pottery barn. So you can see my parents are done redecorating and my mom doesn't wanna spend more money. Okay back to the subject. Well I'm really tired of baby pink. My friend talked me into to it so I wouldn't have baby blue walls and black and white patterns in my room like her. So now I'm stuck with pink :( All I wanna do is have a more grown up looking room before high school. How should i approach my parents? Do you think it's necessary to let your teen have a room they can enjoy during there me time? Y'all give me all your opions.. I'll take em.. Thanks :)