A friend of mine just asked me "What happens if I'm planning my wedding two years out and I pick a color for my bridesmaid dresses that may not be in style when my wedding rolls around?
My advice to her was this:
2 years out is very far to pick things like colors because as we all know, colors change.
If this is the case , I would wait for about 10 months out to pick a color!
This will give you enough time to order the dress and have enough time for alterations if need be!
Generally, styles don't change that much within a year when planning a wedding , so you should be safe!