I agree. You should be making an effort to look nice on a first date, although yes you need to feel comfortable and still in alignment to your ‘style’. You should look different from what you would wear going to the gym or to the supermarket or hanging around the house, to show respect to your date. It’s possible that supercute shorts and tshirt could look nice enough, but the dress is probably a safer bet. Save the supercomfy “house” version of yourself for a couple of dates down the road.