It's really up to you. I have three girls, and honestly I don't think I used bloomers more than once or twice with the youngest and not all that often with the older ones. When they're babies, I don't think it's that huge a deal to just have the tights or even just the diaper under the dress. In the summer maybe use it more, but not absolutely necessary. Once they get a little older, I try to buy more skorts (skirts with built in shorts) so they can still play on the playground, etc. but still have their girl-y look. For church and such they just wear dresses with undies and tights when necessary, but leggings or bloomers/shorts under if out playing. Not a silly question, but not something to worry too much about either. Just enjoy that she can't argue with you over the outfits yet!