I have a few questions: where do you go to buy one?
Most bridal salons carry them - David's is a good place to go for try-on purposes because they have lots of different styles. Many simpler ones can be made yourself - there are lots of patterns/instructions floating around on The Knot. Whatever you do, beware of veils that have crystals on them. If they are rhinestones they show up as black spots in your photos. If they are actually crystals they'll look fine in your photos.
do you have to order it, or do you take it home that day?
Depends on the place. I would call before heading to the salon - they might carry a few of each, or they might do them all as special orders. There are lots of online places too where you can order from once you've decided what style you want.
my dress is ivory. is a white veil gonna look dumb? do they make ivory ones?
They make ivory/off white veils, though becaus the fabric is so sheer the difference between white and ivory might not be very pronounced.
HTH!
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To be yourself in a world that is constantly trying to make you something else is the greatest accomplishment ~ {Ralph Waldo Emerson}
She custom make veils. It took her about two months to make mine. She is extrememely helful and will help you come up with the perfect veil for you depending on your dress and the look you are going for.
She has a picture of my veil up on her site, check it, send her an email. You'll be pleased.