Bad Luck?
To look/purchase a dress before location/date has been set?
To look/purchase a dress before location/date has been set?
I don't think it's bad luck. If you are positive this is THE dress then I say go for it!
I don't think it's bad luck, but just make sure the dress is appropriate for the season - you don't want to wear a thick heavy dress if you plan to have a beach reception in the summer!
It isn't bad luck but you will want to make sure that it fits your season and reception location. You may want to wait a bit and make the other decisions first.