How quick can I get my braces off?

My teeth aren't really crooked, except one of my teeth (the one that is the third to the left of the front tooth on the top ) is twisted so it looks like it is facing in front of me instead of to the side. It didn't even look bad. However, my orthodontist said that my top teeth are supposed to be wider (they are smaller than normal) so he wants to space them apart to make them bigger. I have had them on for three days, and I already see a space between my two front teeth that wasn't there before. Any idea how long this will take? Thanks!