When is a good time to give myself a full makeover without freaking out the people at school?

I want to change my look. All I have are a bunch or sweaters, and a bunch of skinny jeans. I want to expand my wardrobe with a variety of clothes. (and I kind of want to dress a little like Alex from Wizards of Waverly Place) I'm not very popular, and no one really notices me at school, so I enjoyed keeping myself at the down low for all of my school years, but now I want a change in style. Not to make myself known, but just to vary my wardrobe a little. When would I be able to start dressing differently without the people at school thinking I'm weird?