I didn't become lovers with Shuu until end of June, so you're probably fine. He went from crush to love really quick since I kept stalking him around town. Shuu likes the casual clothes, which is nice because they're also the cheapest. :D Wearing the clothes gets you a compliment and I think a boost to his happiness on the date. (You have to be head to toe in the look though, so be prepared for some terrible hats.)
Oh, and red in the heart is love points, blue is friendship points. If you're at crush, I doubt you have to worry about being friendzoned, which apparently is a thing that can happen.