Wedding Salon & changing the order

Hey All,
I ordered my dress from Wedding Salon of Manhasset 2 months ago (a Monique Lhuillier combo of a bustier, skirt, and sash).
I have changed my mind on the sash color.

Is it going to be a huge disaster to change that on the order? I'm sure the designer didn't even start making the dress, my wedding isn't until October. And its only the sash..

I'm going there Saturday to try my dress on and show one of my bridesmaids. I called and have an appointment to put it on again.

Should I call and give them the heads up or should I just talk to them about it when I get there?Is this going to be a big process or what?

i don't see how it could be a big deal. worst comes to worst, they'll just charge you for a new sash... i would just wait until you get there to tell them. i know i am a better negotiator in person.

eta: i'll be there saturday morning - i have my first fitting!