The point is that if you ARE engaged, especially if you are planning to be engaged for a year or less, there's no need to feel silly about hitting the bridal salon circuit pretty early on.
Most bridal salons recommend that you purchase your dress at least 6-9 months before your wedding. Here's why: unless you're buying a sample dress or are purchasing through a retailer like David's Bridal, it will take a while before your dress actually arrives at the store. You do not get to take home the dress you try on. Once you "say yes to the dress," the bridal salon orders that dress from the designer. In most cases, it takes 4-6 months from the time the bridal salon orders your dress to when the dress arrives at the store.
And even THEN, it's not like you can just pick up that dress and be all set for the big day. Wedding dresses come in a really limited selection of sizes, and if your shape roughly resembles that of a human person, odds are you'll need some alterations. You will probably be fitted 2-4 times, with little changes made every time, before the dress fits just right. If you're unfamiliar with the alteration process, here's a picture that should explain everything.
Aside from all of the logistics of getting the gown ready once you've picked it, there is the little matter of actually shopping for the dress. If you are anything like me, Pinterest has probably convinced you that you are completely in love with about 6,000 dresses. There are A LOT of options out there, and you want to give yourself time to try on dresses, think about them, and maybe make a few shopping trips before making your final decision.
So get shopping ladies! If you need a little inspiration, check out Glamour's slideshow of the top wedding dress trends of 2013. And if all of this bridal boutique protocol has you thinking that you're a sample sale/David's Bridal type of girl, you might like Glamour Closet, a bridal store that only sells designer sample dresses. You might also want to check out Melissa Sweet's line for David's Bridal, which I may or may not be obsessed with. Okay, I am. The dresses are gorgeous. I love them. But I'll worry about me and you go shop.